Try making a stamp holder

cad/openscad/.gitignore

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+*.stl

cad/openscad/stamp_holder.scad

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+include <stamp_holder_common.scad>
+
+
+module middle() {
+    difference() {
+        common();
+        ring(size/2-wall_thickness,center_radius);
+        translate([-size/2, size/2-output_radius]) difference() {
+            square(output_radius);
+            translate([output_radius,0]) circle(output_radius);
+        }
+        translate([-size/2, size/2])
+            square([size-15,output_thickness]);
+        translate([size/2-15,total_width-size/2-15])
+            right_arc(15-wall_thickness, 15-wall_thickness-output_thickness);
+        translate([size/2-output_thickness-wall_thickness,0])
+            square([output_thickness,total_width-size/2-15]);
+    }
+}
+linear_extrude(height=wall_thickness) {
+    common();
+    translate([-size / 2, 0])
+        round_rect((wall_thickness+output_thickness)*2,size/2,[1,1,1,1]);
+}
+
+translate([0,0,wall_thickness]) difference() {
+    linear_extrude(height=internal_height) {
+        middle();
+        hull() {
+            translate([-size/2-output_thickness-wall_thickness/2,size/4-wall_thickness/2]) circle(wall_thickness/2);
+            translate([-size/2-output_thickness-wall_thickness/2,-size/4+wall_thickness/2]) circle(wall_thickness/2);
+        }
+    }
+    translate([0,0,internal_height*1/2]) {
+        rotate([0,0,-30]) rotate_extrude(angle=60) square([center_radius-1,1]);
+        rotate([0,0,150]) rotate_extrude(angle=60) square([center_radius-1,1]);
+
+    }
+}
+
+translate([0,0,wall_thickness+internal_height]) linear_extrude(height=wall_thickness/2) {
+    intersection() {
+        middle();
+        translate([0,(wall_thickness+output_thickness)/2]) difference() {
+            round_rect(total_length, total_width, [5, 5, 15, 1]);
+            round_rect(total_length-wall_thickness, total_width-wall_thickness, [5 - wall_thickness/2, 5-wall_thickness/2, 15-wall_thickness/2, 1-wall_thickness/2]);
+            
+        }
+    }
+    hull() {
+        translate([-size/2-output_thickness-wall_thickness/2,size/4-wall_thickness/2]) circle(wall_thickness/4);
+        translate([-size/2-output_thickness-wall_thickness/2,-size/4+wall_thickness/2]) circle(wall_thickness/4);
+    }
+
+
+}

cad/openscad/stamp_holder_common.scad

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+wall_thickness = 1.5;
+output_thickness = 1.5;
+internal_height = 26;
+center_radius = 10;
+output_radius = 3;
+size = 40;
+$fn = 500;
+
+total_length = size;
+total_width = size + wall_thickness + output_thickness;
+total_height = internal_height + wall_thickness * 3/2;
+
+
+module round_rect(length, width, radii) {
+    points = [
+        [-length/2 + radii[0], -width/2 + radii[0]],
+        [ length/2 - radii[1], -width/2 + radii[1]],
+        [ length/2 - radii[2],  width/2 - radii[2]],
+        [-length/2 + radii[3],  width/2 - radii[3]]
+       ];
+    
+    hull() {
+        for(i = [0:3]) {
+            translate(points[i]) circle(r=radii[i]);
+        }
+    }
+}
+
+module ring(or, ir) {
+    difference() {
+        circle(or);
+        circle(ir);
+    }
+}
+
+module right_arc(or, ir) {
+    intersection() {
+        ring(or, ir);
+        square(or);
+    }
+}
+
+module common() {
+    difference() {
+        translate([0,(wall_thickness+output_thickness)/2])
+            round_rect(total_length, total_width, [5, 5, 15, 1]);
+        circle(center_radius - wall_thickness);
+    }
+}

cad/openscad/stamp_holder_top.scad

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+include <stamp_holder_common.scad>
+
+module finger() {
+    translate([center_radius-wall_thickness*2-0.25,0,0]) square([wall_thickness,internal_height*1/3]);
+}
+
+module hook() {
+    translate([center_radius-wall_thickness*2-0.25,0,0]) {
+        square([wall_thickness,internal_height*1/3+2]);
+        translate([wall_thickness,internal_height*1/3])
+            polygon([[0,-1],[1,0.5],[0,2]]);
+    }
+}
+
+linear_extrude(wall_thickness) {
+    difference() {
+        mirror([1,0,0]) {
+            translate([0,(wall_thickness+output_thickness)/2])
+                round_rect(total_length, total_width, [5, 5, 15, 1]);
+            translate([-size / 2, 0])
+                round_rect((wall_thickness+output_thickness)*2,size/2,[1,1,1,1]);
+        }
+        circle(center_radius-wall_thickness*2-0.25);
+    }
+}
+
+translate([0,0,wall_thickness]) linear_extrude(wall_thickness/2) {
+    difference() {
+        mirror([1,0,0]) {
+            translate([0,(wall_thickness+output_thickness)/2])
+                round_rect(total_length-wall_thickness-.5, total_width-wall_thickness-.5, [5, 5, 15, 1]);
+            difference() {
+                hull() {
+                    translate([-size/2-output_thickness-wall_thickness/2,size/4-wall_thickness/2]) circle(wall_thickness/2);
+                    translate([-size/2-output_thickness-wall_thickness/2,-size/4+wall_thickness/2]) circle(wall_thickness/2);
+                }
+                hull() {
+                    translate([-size/2-output_thickness-wall_thickness/2,size/4-wall_thickness/2]) circle(wall_thickness*3/8);
+                    translate([-size/2-output_thickness-wall_thickness/2,-size/4+wall_thickness/2]) circle(wall_thickness*3/8);
+                }
+            }
+        }
+        circle(center_radius-wall_thickness*2-0.25);
+    }
+}
+
+translate([0,0,wall_thickness*3/2]) linear_extrude(internal_height / 6) {
+    ring(center_radius-wall_thickness-0.25, center_radius-wall_thickness*2-0.25);
+}
+
+translate([0,0,wall_thickness*3/2+internal_height/6]) {
+    rotate([0,0,-25]) rotate_extrude(angle=50) hook();
+    rotate([0,0,35]) rotate_extrude(angle=110) finger();
+    rotate([0,0,155]) rotate_extrude(angle=50) hook();
+    rotate([0,0,215]) rotate_extrude(angle=110) finger();
+
+}