Hi,
10mm thick clear acrylic. I think it was around 20K spindle speed with a 1/8" upcut 2 flute carbide bit 3mm DOC. I left 0.2mm all the way around both inside and out and then did a final pass at full depth. I did the inside first, then re clamped though those cutouts and then did the outside.
Finishing the edges was done by flame polishing. I used a small butane blowtorch - about the size of a cigarette lighter - that gives a blue flame. A quick pass along the edge and it melts the surface. Pretty cool to watch it go from white to clear. Took very little practice to get the technique.
Lighting is via blue LED's inserted into 5mm holes drilled up from the bottom of each letter. Powered by a 3v battery pack with a switch.