First a disclaimer, am not a Botter, but have always liked this forum, and don't discount the possibility of owning a Bot sometime down the road.
That said, these can just as well be made with a Bot. Both are vectorart files that have been carved -3D, substracted mode. Roughing I use a .25 endmill, finish a .05 tapered ball nose, commonly used for 3D in wood.
1st one is a Jesus bust done in 3/8" plexi, not much room for depth with 3/8", but as you can see, it is possible. Used just about all the thickness I had available, came out very nice. Lettering was then etched with a diamond drag bit, and set in a custom base with a RGB strip.
2nd was done in 1" thick plexi, plenty of room for depth with 1", probably went near .75" deep. Came out very nice, is about 12x8", sure to appeal to firearm enthusiasts.
I have tried these in .5" plexi as well, did a very nice praying hands design, and I think .5 is ideal for these.
The normal caveats when routing plexi apply to these, slow RPM's as possible and high feed rates to avoid any melting issues. These are fun to make, open up new areas of creativity, and sell pretty well, certainly attract attention wherever they are.