For thin acrylic (2mm) you can use the cutter. For thicker acrylic it's difficult to get a neat cut without power tools - jig or rotary saw. For circular cuts: you need a rotary tool or a drill/jig combination - drill a hole to insert the jig and with the jig on a slow speed ( to prevent the acrylic from excessive vibration) run the jigsaw around your pencilled circle.

A steady hand is also required.