You can get those acrylic cutter from DIY store, the way to cut is like cutting glass.
Use the cutter to cut a deep line/groove into the acrylic, bend the sheet away from the groove and it will snap off.....the tricky part is the line/groove cutting and bending the acrylic with support for snapping.
I usually place the sheet in between 2 plank, align the line before attempting to bend for it to snap off accurately on the line.
Hope it helps.