HDPE/Acrylic/Nylon/RG1000

[Roboteernat]

I would plan your parts on the big sheet, then see what managable size you can cut it to to neatly trim the parts from that.

jigsaw - if budget is problem then the cheapo jigsaw from argos shall be fine - £17.99 http://www.argos.co.uk/product/7110948 but if budget is better then i would get a better one with variable speed control and bigger wattage. i bought a battery one from Lidl for £39.99
People have used fine cut hand saws to cut it too, i guess this will also lead to straighter edges! also clamping some wood to run against will give you a nice edge