diff --git a/README.md b/README.md
index a2d1826..a0a8303 100644
--- a/README.md
+++ b/README.md
@@ -431,6 +431,13 @@ description: circlular geometry.
 *uses:* data_1=tolorence
 
 
+**nut_holder**
+
+*description:* nut holder
+
+*uses:* size_x=top diameter or x size in mm, size_y=bottom diameter or y size in mm, size_z=holder height in mm, data_0="m2" or "m2.5" or "m3" or "m4", data_1="default" or "sloped" or "trap"
+
+
 #### Sub class only “types”
 
 
diff --git a/sbc_case_builder_accessories.cfg b/sbc_case_builder_accessories.cfg
index bcae481..4708fee 100644
--- a/sbc_case_builder_accessories.cfg
+++ b/sbc_case_builder_accessories.cfg
@@ -907,18 +907,22 @@ accessory_data = [
              "model","vent_panel_hex",144,11.77,64,"top",[0,90,0],["case",false,false,false],62,107.43,3,5.0,1.6,"y",14,                // model vent cover
              "platter","vent_panel_hex",-200,13.77,0,"top",[0,0,0],["case",false,false,false],62,107.43,3,5.0,1.6,"y",14,               // model vent cover
              "suball","rectangle",111,26.77,64,"top",[0,90,0],["case",true,false,false],62,77.43,4,0,0,"",[2,2,2,2],                    // vent opening
-             "sub","round",111,16.57,57,"top",[0,90,0],["case",true,false,false],9,0,4,0,0,"",0,                                        // vent cover screw hole
-             "sub","round",111,16.57,9,"bottom",[0,90,0],["case",true,false,false],9,0,4,0,0,"",0,                                      // vent cover screw hole
-             "sub","round",111,114.4,57,"top",[0,90,0],["case",true,false,false],9,0,4,0,0,"",0,                                        // vent cover screw hole
-             "sub","round",111,114.4,9,"bottom",[0,90,0],["case",true,false,false],9,0,4,0,0,"",0,                                      // vent cover screw hole
+             "sub","round",111,16.57,57,"top",[0,90,0],["case",true,false,false],7,0,4,0,0,"",0,                                        // vent cover screw hole
+             "sub","round",111,16.57,9,"bottom",[0,90,0],["case",true,false,false],7,0,4,0,0,"",0,                                      // vent cover screw hole
+             "sub","round",111,114.4,57,"top",[0,90,0],["case",true,false,false],7,0,4,0,0,"",0,                                        // vent cover screw hole
+             "sub","round",111,114.4,9,"bottom",[0,90,0],["case",true,false,false],7,0,4,0,0,"",0,                                      // vent cover screw hole
              "sub","round",3.81,17.78,35,"top",[0,0,0],["sbc-case_z",true,true,true],6.5,0,19,0,0,"",0,                                 // sub screw hole
              "sub","round",3.81,106.19,35,"top",[0,0,0],["sbc-case_z",true,true,true],6.5,0,19,0,0,"",0,                                // sub screw hole
              "sub","round",106.04,24.77,35,"top",[0,0,0],["sbc-case_z",true,true,true],6.5,0,19,0,0,"",0,                               // sub screw hole
              "sub","round",106.04,106.2,35,"top",[0,0,0],["sbc-case_z",true,true,true],6.5,0,19,0,0,"",0,                               // sub screw hole
-             "add2","standoff",140,16.57,57,"top",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],        // vent cover nut holder
-             "add2","standoff",140,16.57,9 ,"bottom",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],     // vent cover nut holder
-             "add2","standoff",140,114.4,57,"top",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],        // vent cover nut holder 
-             "add2","standoff",140,114.4,9 ,"bottom",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],     // vent cover nut holder
+             "add2","nut_holder",144,16.57,57,"top",[0,270,0],["case",false,false,false],8,16,5,"m3","sloped",0,0,        // vent cover nut holder
+             "add2","nut_holder",144,16.57,9 ,"bottom",[0,270,0],["case",false,false,false],8,16,5,"m3","sloped",0,0,     // vent cover nut holder
+             "add2","nut_holder",144,114.4,57,"top",[0,270,0],["case",false,false,false],8,16,5,"m3","sloped",0,0,        // vent cover nut holder 
+             "add2","nut_holder",144,114.4,9 ,"bottom",[0,270,0],["case",false,false,false],8,16,5,"m3","sloped",0,0,     // vent cover nut holder
+//             "add2","standoff",140,16.57,57,"top",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],        // vent cover nut holder
+//             "add2","standoff",140,16.57,9 ,"bottom",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],     // vent cover nut holder
+//             "add2","standoff",140,114.4,57,"top",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],        // vent cover nut holder 
+//             "add2","standoff",140,114.4,9 ,"bottom",[0,90,0],["case",false,false,false],0,0,0,0,0,0,[10,4,3.2,10,2.5,3,1,0,0,0,0],     // vent cover nut holder
              "sub","rectangle",-4,100.5,3,"top",[0,0,0],["sbc-case_z",true,true,true],14,4,20,0,0,"",[1,1,1,1],                         // sub rectangle
              "sub","rectangle",100.5,17,30,"top",[0,0,0],["sbc-case_z",true,true,true],9,4,10,0,0,"",[1,1,1,1],                         // sub rectangle
              "model","standoff",78,127,8.65,"top",[-90,0,0],["case",false,false,true],0,0,0,0,0,0,[5.75,10,3.2,10,0.01,0,0,1,0,0,0],    // standoff
diff --git a/sbc_case_builder_library.scad b/sbc_case_builder_library.scad
index 6b8ed9c..40e65f8 100644
--- a/sbc_case_builder_library.scad
+++ b/sbc_case_builder_library.scad
@@ -51,7 +51,8 @@
     20221207 version 2.0.3 added double_stacked_usb3-usb2, hd35_vtab(side) and supporting code
     2023xxxx version 2.0.x added h3_port_extender(style, mask = false), hk_pwr_button(mask = false), keyhole(keysize, mask = false),
                            vent_hex(cells_x, cells_y, cell_size, cell_spacing, orientation) and supporting code, dsub(dsubsize, mask = false),
-                           vent_panel_hex(x, y, thick, cell_size, cell_spacing, border, borders),
+                           vent_panel_hex(x, y, thick, cell_size, cell_spacing, border, borders), 
+                           added nut_holder(nut, style, dia_x, dia_y, height)
         
     see https://github.com/hominoids/SBC_Case_Builder
     
@@ -125,8 +126,10 @@
     hk_pwr_button(mask = false)
     keyhole(keysize, mask = false)
     vent_hex(cells_x, cells_y, cell_size, cell_spacing, orientation)
-    dsub(dsubsize, mask = false)
     vent_panel_hex(x, y, thick, cell_size, cell_spacing, border, borders);
+    dsub(dsubsize, mask = false)
+    nut_holder(nut, style, dia_x, dia_y, height)
+    
 */
 
 use <./lib/fillets.scad>;
@@ -267,7 +270,8 @@ module add(type,loc_x,loc_y,loc_z,face,rotation,size_x,size_y,size_z,data_1,data
         translate([loc_x,loc_y,loc_z])  rotate(rotation) fan_cover(size_x, size_z);
     }
     if(type == "vent_panel_hex") {
-        translate([loc_x,loc_y,loc_z])  rotate(rotation) vent_panel_hex(x=size_x, y=size_y, thick=size_z, cell_size=data_1, cell_spacing=data_2, border=data_4, borders=data_3);
+        translate([loc_x,loc_y,loc_z])  rotate(rotation) vent_panel_hex(x=size_x, y=size_y, thick=size_z, 
+            cell_size=data_1, cell_spacing=data_2, border=data_4, borders=data_3);
     }
     if(type == "feet") {
         translate([loc_x,loc_y,loc_z])  rotate(rotation) feet(size_x, size_z);
@@ -293,6 +297,9 @@ module add(type,loc_x,loc_y,loc_z,face,rotation,size_x,size_y,size_z,data_1,data
     if(type == "dsub") {
         translate([loc_x,loc_y,loc_z]) rotate(rotation) dsub(data_4); 
     }
+    if(type == "nut_holder") {
+        translate([loc_x,loc_y,loc_z]) rotate(rotation) nut_holder(data_1, data_2, size_x, size_y, size_z); 
+    }
 }
 
 
@@ -3767,3 +3774,100 @@ module dsub(dsubsize, mask = false) {
         }
     }
 }
+
+
+//
+// nut_holder(nut, style, dia_x, dia_y, height)
+//            nut = "m2", "m2.5", "m3", "m4"
+//            style = "default", "sloped", "trap"
+//            dia_x = top diameter or x size in mm
+//            dia_y = bottom diameter or y size in mm
+//            height = holder height in mm
+//
+module nut_holder(nut, style, dia_x, dia_y, height) {
+
+
+nuts = [[2,4,1.6],         // m2 size, diameter, height
+        [2.5,5,2],         // m2.5 size, diameter, height
+        [3,5.5,2.4],       // m3 size, diameter, height
+        [4,7,3.2]];        // m4 size, diameter, height
+
+$fn = 180;
+    
+    if( style == "default") {
+        difference() {
+            cylinder(d=dia_x, h=height);
+            if(nut == "m2") {
+                translate([0, 0, -1]) cylinder(d=nuts[0][0]+.25, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[0][1]*2/sqrt(3), h=height, $fn=6);
+            }
+            if(nut == "m2.5") {
+                translate([0, 0, -1]) cylinder(d=nuts[1][0]+.25, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[1][1]*2/sqrt(3), h=height, $fn=6);
+            }
+            if(nut == "m3") {
+                translate([0, 0, -1]) cylinder(d=nuts[2][0]+.5, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[2][1]*2/sqrt(3), h=height, $fn=6);
+            }
+            if(nut == "m4") {
+                translate([0, 0, -1]) cylinder(d=nuts[3][0]+.5, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[3][1]*2/sqrt(3), h=height, $fn=6);
+            }
+        }
+    }
+    if( style == "sloped") {
+        difference() {
+            cylinder(d2=dia_x, d1=dia_y, h=height);
+            if(nut == "m2") {
+                translate([0, 0, -1]) cylinder(d=nuts[0][0]+.25, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[0][1]*2/sqrt(3), h=height, $fn=6);
+            }
+            if(nut == "m2.5") {
+                translate([0, 0, -1]) cylinder(d=nuts[1][0]+.25, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[1][1]*2/sqrt(3), h=height, $fn=6);
+            }
+            if(nut == "m3") {
+                translate([0, 0, -1]) cylinder(d=nuts[2][0]+.5, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[2][1]*2/sqrt(3), h=height, $fn=6);
+            }
+            if(nut == "m4") {
+                translate([0, 0, -1]) cylinder(d=nuts[3][0]+.5, h=height+2);
+                translate([0, 0, 2]) cylinder(d=nuts[3][1]*2/sqrt(3), h=height, $fn=6);
+            }
+        }
+    }
+    if( style == "trap") {
+        if(nut == "m2") {
+            difference() {
+                translate([-dia_x/2, -dia_y/2, 0]) cube([dia_x, dia_y, height]);
+                translate([0, 0, -1]) cylinder(d=nuts[0][0]+.25, h=height+2);
+                translate([0, 0, 2]) rotate([0,0,30]) cylinder(d=nuts[0][1]*2/sqrt(3), h=nuts[0][2], $fn=6);
+                translate([-nuts[0][1]/2, 0, 2]) cube([nuts[0][1], dia_x, nuts[0][2]]);
+            }
+        }
+        if(nut == "m2.5") {
+            difference() {
+                translate([-dia_x/2, -dia_y/2, 0]) cube([dia_x, dia_y, height]);
+                translate([0, 0, -1]) cylinder(d=nuts[1][0]+.325, h=height+2);
+                translate([0, 0, 2]) rotate([0,0,30]) cylinder(d=nuts[1][1]*2/sqrt(3), h=nuts[1][2], $fn=6);
+                translate([-nuts[1][1]/2, 0, 2]) cube([nuts[1][1], dia_x, nuts[1][2]]);
+            }
+        }
+        if(nut == "m3") {
+            difference() {
+                translate([-dia_x/2, -dia_y/2, 0]) cube([dia_x, dia_y, height]);
+                translate([0, 0, -1]) cylinder(d=nuts[2][0]+.5, h=height+2);
+                translate([0, 0, 2]) rotate([0,0,30]) cylinder(d=nuts[2][1]*2/sqrt(3), h=nuts[2][2], $fn=6);
+                translate([-nuts[2][1]/2, 0, 2]) cube([nuts[2][1], dia_x, nuts[2][2]]);
+            }
+        }
+        if(nut == "m4") {
+            difference() {
+                translate([-dia_x/2, -dia_y/2, 0]) cube([dia_x, dia_y, height]);
+                translate([0, 0, -1]) cylinder(d=nuts[3][0]+.5, h=height+2);
+                translate([0, 0, 2]) rotate([0,0,30]) cylinder(d=nuts[3][1]*2/sqrt(3), h=nuts[3][2], $fn=6);
+                translate([-nuts[3][1]/2, 0, 2]) cube([nuts[3][1], dia_x, nuts[3][2]]);
+            }
+        }
+    }
+}
\ No newline at end of file