Great work as always, Xxray...
I've attempted to do the 3D on plexi, but my machine's maximum's feed is about 150 ipm (I have reduction gears... 7.2 to 1... for more precision) and a milwaukee router with a minimum rpm of 10,000 rpms. I just added a mount for a dremel, so I will hopefully be able to cut plexi rather than melt plexi.
Meanwhile, I'm curious... what rpms are you using at the feed speeds of 200 and 250 ipm. Also, do you (or other members) know of any sites which might have various ratios of rpms, feed speeds and bit sizes for good cutting for woods, plastics, etc.?
Perhaps the group might be able to come up with some good data to make a chart if we submit what is working for us on various material.
Just a thought...
Again, nice work indeed!