Double sided tape works. When I was cutting thin acrylic I used blue painter’s tape and superglue. Put tape on your part, and tape on the spoil board. Run a bead of superglue on the tape and stick it to the other piece of tape. Hold it down until the glue sets, or use an accelerator. The tape will hold the parts down while you’re cutting, but will pull off fairly easily with a putty knife. Got the idea from a guy on youtube cutting aluminum parts on a mill.