toybrick()

OpenSCAD program to generate toy bricks compatible with many popular toy brick systems that I cannot name here.

The resulting models can be made real through 3D printers or CNC machines.

This is an example of how to use OpenSCAD to program 3D models and thinking in terms of constructive solid geometry. Follow along...

Intro to OpenSCAD

Before you begin, learn the 4 important concepts in my quick deck:

Programming 3D Objects with OpenSCAD

Ok, done that? Onwards.

What is this?

This is a very simple 3D library that has one function:

toybrick(length, width);

It outputs a 3D model.

Examples

Pssst! Did you know GitHub has an interactive 3D viewer? Mind. Blown.

Code	Top	Bottom
toybrick(1,1) 3D viewer
toybrick(4,2) 3D viewer
toybrick(5,3) 3D viewer
toybrick(6,6) 3D viewer
toybrick(10,2) 3D viewer

Implementation

Woah there. If you skipped the Programming 3D Objects with OpenSCAD deck, go back. It's really short. You need to understand the 4 fundamental concepts first.

High level

A toy brick consists of:

• a body (main hollow brick)
• n × m top studs
• (n-1) × (m-1) inner tubes

That's it.

Note: The variables used for dimensions are defined in toybrick-dimensions.scad

Body

Well this is easy. Take a block (scad cube()), then hollow it out by calling difference() on another block:

module body(units_wide, units_long) {
	difference() {
		cube([
				units_wide * length,
				units_long * length,
				height]);
		translate([wall_thickness, wall_thickness, 0]) {
			cube([
					units_wide * length - wall_thickness * 2,
					units_long * length - wall_thickness * 2,
					height - wall_thickness]);
		}
	}
}

cube1	cube2	difference(cube1, cube2)

Stud

Even easier, it's just a cylinder() translated to the right place on top of a block:

module stud(unit_x, unit_y) {
	translate([
			(unit_x + 0.5) * length,
			(unit_y + 0.5) * length,
			height]) {
		cylinder(d=stud_diameter, h=stud_height);
	}
}

cylinder

Inner tube

Another cylinder(), hollowed out using the difference() of an inner cylinder():

module tube(unit_x, unit_y) {
	translate([
			unit_x * length,
			unit_y * length,
			0]) {
		difference() {
			cylinder(d=tube_diameter, h=height - wall_thickness);
			cylinder(d=tube_diameter - wall_thickness * 2, h=height - wall_thickness);
		}
	}
}

cylinder1	cylinder2	difference(cylinder1, cylinder2)

Bringing it all together

Now we call our smaller modules to create the body(), and a for loop to add the stud()s and tube()s:

module toybrick(units_wide, units_long) {

	// Step 1: Make the body (main hollow brick)
	body(units_wide, units_long);

	// Step 2: Now loop over x,y...
	for (x=[0 : units_wide - 1], y=[0 : units_long - 1]) {

		// Top stud
		stud(x, y);

		// If beyond the first column and row, inner tube
		if (x > 0 && y > 0) {
			tube(x, y);
		}

	}

	// That's it!
}

Tada!

Code	Top	Bottom
toybrick(4,2) 3D viewer

The final code:

• toybrick.scad
• toybrick-dimensions.scad
• example1.scad (standalone example)

Building on it

Now we have a basic toybrick() we can make programs that use it to make other things.

Like a pyramid:

layers = 6;

for (i = [ 1 : layers ]) {
  translate([length * i * -1,
             length * i * -1,
             height * (i * -1 + layers)]) {
    toybrick(i * 2, i * 2);
  }
}

3D viewer

What next?

Go read the OpenSCAD manual, look for inspiration on Thingiverse and follow me on Twitter.

ABC: Always Be Creating