Ive seen several posts where folks have tried to use 3/16" acrylic in the black “hockey puck” LED bases. Usually they say they can be successful getting them to work if they force the acrylic into the slot. The slot is 4mm, so that’s a little less than a mm smaller that 3/16. That is a lot of forcing!
I found a solution that works great: Simply do a “Draft Graphic (1000/FULL) rectangle engrave on the bottom tab (the 3 x 1/2” tab that fits into the base). The tab will then fit perfectly into the base, and the result is stunning, much better than using the 1/8" acrylic.
The same method could be used with the PG thick acrylic (.25"), but you might need to experiment a little to get the proper engrave depth. Also, keep in mind that acrylic thickness can vary.