If the plastic is clear, it tends to disappear into the background, and you see only the model. You can buy plastic sheets in a variety of sizes and colors. Most stores have a scrap pile that may have the exact piece you are looking for. The block is now ready for use as a stand. Working with plastic is only slightly harder than working with wood.
Plastic can crack and break, so always use sharp, fine-tooth saws.
A hacksaw or coping saw with a metal working blade can be used on acrylic plastic sheet. You can use the paper wet or dry. After the plastic piece has been cut to size and sanded, you can mount the model on it. Use white glue or 5-minute epoxy, as you did with the wood stand. Don t use model cement to glue the model to the plastic.