diff --git a/scad/conf/utils.scad b/scad/conf/utils.scad
index c1bdd0d..7163a33 100644
--- a/scad/conf/utils.scad
+++ b/scad/conf/utils.scad
@@ -54,31 +54,6 @@ module nut_trap_support(h, r, r2 = 0) {
     }
 }
 
-function nut_trap_radius(nut) = nut_radius(nut) + layer_height / 4;
-function nut_trap_flat_radius(nut) = nut_trap_radius(nut) * cos(30);
-
-module nut_trap(screw_r, nut_r, depth, horizontal = false, supported = false) {
-    render(convexity = 5) union() {
-        if(horizontal) {
-            if(screw_r)
-                teardrop_plus(r = screw_r, h = 200, center = true);
-            cylinder(r = nut_r + layer_height / 4, h = depth * 2, center = true, $fn = 6);
-        }
-        else {
-            difference() {
-                union() {
-                    if(screw_r)
-                        poly_cylinder(r = screw_r, h = 200, center = true);
-                    cylinder(r = nut_r, h = depth * 2, center = true, $fn = 6);
-                }
-                if(supported)
-                    translate([0, 0, depth - eta])
-                        cylinder(r = nut_r, h = layer_height, center = false);
-            }
-        }
-    }
-}
-
 module part_screw_hole(screw, nut, horizontal = false, supported = false) {
     screw_r = screw_clearance_radius(screw);
     if(nut)
@@ -107,7 +82,7 @@ module right_triangle(width, height, h, center = true) {
 
 module rounded_square(w, h, r)
 {
-    union() {
+    hull() {
         square([w - 2 * r, h], center = true);
         square([w, h - 2 * r], center = true);
         for(x = [-w/2 + r, w/2 - r])
diff --git a/scad/vitamins/nuts.scad b/scad/vitamins/nuts.scad
index fb29af9..ce2fe5c 100644
--- a/scad/vitamins/nuts.scad
+++ b/scad/vitamins/nuts.scad
@@ -7,14 +7,14 @@
 //
 // Washers
 //
-M2_nut    =   [2, 4.9, 1.6, 2.4,  M2_washer,     M2_nut_trap_depth];
-M2p5_nut  = [2.5, 5.8, 2.2, 3.8,  M2p5_washer, M2p5_nut_trap_depth];
-M3_nut      = [3, 6.4, 2.4, 4,    M3_washer,     M3_nut_trap_depth];
-M4_nut      = [4, 8.1, 3.2, 5,    M4_washer,     M4_nut_trap_depth];
-M5_nut      = [5, 9.2,   4, 6.25, M5_washer,     M5_nut_depth];
-M6_nut      = [6, 11.5,  5, 8,    M6_washer,     M6_nut_depth];
-M6_half_nut = [6, 11.5,  3, 8,    M6_washer,     3];
-M8_nut      = [8, 15,  6.5, 8,    M8_washer,     M8_nut_depth];
+M2_nut    =   [2, 4.9, 1.6, 2.4,  M2_washer,     M2_nut_trap_depth, 5/2];
+M2p5_nut  = [2.5, 5.8, 2.2, 3.8,  M2p5_washer, M2p5_nut_trap_depth, 5.9 / 2];
+M3_nut      = [3, 6.4, 2.4, 4,    M3_washer,     M3_nut_trap_depth, M3_nut_radius];
+M4_nut      = [4, 8.1, 3.2, 5,    M4_washer,     M4_nut_trap_depth, M4_nut_radius];
+M5_nut      = [5, 9.2,   4, 6.25, M5_washer,     M5_nut_depth,      M5_nut_radius];
+M6_nut      = [6, 11.5,  5, 8,    M6_washer,     M6_nut_depth,      M6_nut_radius];
+M6_half_nut = [6, 11.5,  3, 8,    M6_washer,     3,                 M6_nut_radius];
+M8_nut      = [8, 15,  6.5, 8,    M8_washer,     M8_nut_depth,      M8_nut_radius];
 
 function nut_radius(type) = type[1] / 2;
 function nut_flat_radius(type) = nut_radius(type) * cos(30);
@@ -100,3 +100,27 @@ module wingnut(type) {
             cylinder(r = hole_rad, h = thickness + 2);
     }
 }
+function nut_trap_radius(nut, horizontal = true, snug = true) = (snug ? nut_radius(nut) : nut[6]) + (horizontal ? layer_height / 4 : 0);
+function nut_trap_flat_radius(nut, horizontal = true, snug = true) = nut_trap_radius(nut, horizontal, snug) * cos(30);
+
+module nut_trap(screw_r, nut_r, depth, horizontal = false, supported = false) {
+    render(convexity = 5) union() {
+        if(horizontal) {
+            if(screw_r)
+                teardrop_plus(r = screw_r, h = 200, center = true);
+            cylinder(r = nut_r + layer_height / 4, h = depth * 2, center = true, $fn = 6);
+        }
+        else {
+            difference() {
+                union() {
+                    if(screw_r)
+                        poly_cylinder(r = screw_r, h = 200, center = true);
+                    cylinder(r = nut_r, h = depth * 2, center = true, $fn = 6);
+                }
+                if(supported)
+                    translate([0, 0, depth - eta])
+                        cylinder(r = nut_r, h = layer_height, center = false);
+            }
+        }
+    }
+}