I designed this valve shim placement tool to aid in my recent valve adjustment on my 2004 BMW E46 M3. After viewing the picture of this special tool online, I decided it wasn't worth the money to order one, so I purchased some magnets and printed one instead.

The magnet I used is a 8mm(0.315") Diameter x 3mm(0.118") Height, and was embedded into the base during the printing stage. I used the color change feature of PrusaSlicer to stop the print before the top layer and inserted the magnet.

I printed both parts out of PETG and glued them together with cyanoacrylate.
The tool was tested on my engine and worked perfectly. I even did the hard to reach rear valves with this homemade tool.