Plast-aid does not stick to polyethylene.  You can create a mechanical bond with polyethylene if you are able to have the Plast-aid encase a portion of the part that can not be pulled out. 

In fact our mix cup is made from polyethylene. Because the cup is flexible and there is nothing interfering, you can pop cured Plast-aid out of it. If for some reason you need more cups, we sell them along with the sticks in our web store.