With a jigsaw and a metal cutting blade...

First draw your planned hole with pencil onto the acrylic. Then drill a hole within the circle but NOT on the line of the circle enough to enable the blade of the jigsaw in. Then cut along the circle that you've drawn.

The trick is the speed of the cut. Not too fast, not too slow and a low speed on the jigsaw blade reciprocation. Takes some experience though... (as with everything in life).