This is a simple rotary 3-bit absolute encoder that I designed to be 3d printed and assembled with no screws or supports. The base and top act as housing to hold 2in x 2in protoboards, with the base holding 3 LEDs and the top holding 3 photoresistors.

The gray encoder disk was designed by SciJoy on their YouTube series and breaks the wheel into 8 sections:
{0, 0, 0}, // Section 1
{0, 0, 1}, // Section 2
{1, 0, 1}, // Section 3
{1, 1, 1}, // Section 4
{0, 1, 1}, // Section 5
{0, 1, 0}, // Section 6
{1, 1, 0}, // Section 7
{1, 0, 0} // Section 8

The holes for the encoder wheel to spin freely are designed for a Lego Mindstom axel at 0.2in diameter, but the encoder disk hole is not big enough so you will have to make it larger post-print.

Everything snaps together, but is pretty much a one-time use so make sure you assemble everything correctly at the proper spacings.

I left the backs open to save resources and allow you to run jumper cables out the back or add weight to the bottom.

• Vinidu Geevaratne