I would not be afraid to drill with the perspex. Perspex should withstand almost anything of pressure and deformation. If you are afraid of the drill slipping sideways and scratching the perspex, the above mentioned tape trick is good advice. Even better is to use a pin punch in addition, to mark the drill hole. You could use an automatic punch,one that releases the pin suddenly and impacts the metal when you exort a certain pressure on the punch. On an ordinary punch you would have to use a hammer, not so good. Then use a rather thin burr to penetrate, followed by another burr with the right size.
