Remove any labels or stickers from your jar. Goo-Gone works well for this. Put the jar on top of the RGB matrix and draw vertical cut lines with a permanent marker along the edges of the matrix.

Be extremely careful using any cutting tool and wear appropriate clothing and take necessary precautions.

Use a box cutter or rotary tool to carefully cut along the cut lines, creating an open "flat" area to attach your RGB matrix.

Clean up the edges with flush cutters or a grinder, if needed. Try to get them as straight as possible. The jar should lay perfectly flat on the table without wiggling, if you put the cut side down.

Cover the raw edges with a piece of 1" gaffer's tape.

If your jar is the same height or shorter than your RGB matrix, you'll need to modify the lid as well. Put the lid on the jar and mark your cut line, then cut the lid to size with a saw or rotary tool. 

Use a rotary tool or heat tool to make an opening to drop the money in.

Attach your sensor to the underside of the lid with the laser pointing toward the opening. Place it within 20mm of the opening if possible - that way you won't need to modify the sample code.

If your build requires a different alignment, you can modify the code without too much trouble.

Attach the RGB matrix to the back of the jar with the lights pointing inwards. Be sure to line it up evenly on the bottom so the jar doesn't tip over - it is a little bit back-heavy when it's not full of money. (So let's get on with it, and get those quarters rolling in!)

If you've already uploaded the code, test it out by dropping some coins or bills through the slot. Each time a tip is dropped in, you will see a Thank You animation on the pixels.


Power the project via the USB port on the Matrix Portal. You can plug directly into a power supply (like this one), or plug in a USB battery if you're busking outdoors and need a mobile tip jar.

This guide was first published on Nov 24, 2020. It was last updated on Jul 14, 2024.

This page (Build the Tip Jar) was last updated on Mar 08, 2024.

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