one completely random thing you might consider is using multiple sheets of 1/16 clear acrylic.
break your design elements into multiple layers. if you divided it into 8 layers, you could etch on 8 different sheets and sandwich them together and use something to side light the resulting 1/2" slab.
or maybe if you reversed every other layer, you could etch on both sides of 1/16 acrylic and sandwich the 8 layers on 4 sheets and only be 1/4" thick.
or it may be a complete fail. but i’m kinda thinking about the piece that @xabbess did here.