I abandoned plexi long ago as it ALWAYS cracked on the last hole I drilled

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Lexan is about 50% more expensive but will never crack, and is easy to work with. You simply need to score it deep enough with a straight edge and sharp blade (Xacto etc) and it'll snap along the straight edge if you apply enough bending pressure against a solid edge.
As for holes, you can buy a 1 1/8" Blu-mol bi-metal hole saw. It is not a spade bit but instead looks like a drill bit with a tube on the end.
search for "blu-mol 6533" on homedepot.com.
Not only will it cut through Lexan (like butter) but will cut through steel control panels easily enough too (be sure to use a corded drill, my rechargable dies on steel hole drilling). They are guaranteed for life!