My favorite tool for working with PE is a simple ceramic tile. They are about 0.50 each at stores like Lowes or Home Depot. They are very hard and very flat and come in very handy.
I use an X-Acto knife with a #10 blade (rounded, not the pointed #11 blade) and a ceramic tile to get the parts off the frets. The tile keeps the parts from bending, but it's kind of rough on the X-Acto blades. Use a very small file to carefully clean up the part after cutting it loose.
PE parts are easily bent. Another use for a ceramic tile is to straighten them back out. Put the part on the tile and flatten it back out with the back end of an X-Acto knife.