I bought a 4W LED bulb for 20cm for 9.9 yuan, and it just happened to be perfect for my printer. I measured the dimensions of the clamps I had and referenced some lamp holder designs. The original design called for a width of 20mm, but to test it faster, I printed a 10mm-wide version first. Surprisingly, the first version fit perfectly, so I ended up printing two 10mm ones to use. They turned out to be quite sturdy and worked just fine. Both widths are included in the package.