HDPE is the plastic used in many household containers including gallon sized milk jugs. I made an Instructable a while back on the processing of HDPE using a blender and toaster oven. Well, I've been banned from touching the kitchen blender! So now I'm just rough cutting the plastic with a razor knife. Honestly? It works fine.
I had to melt down about 7 milk jugs and 3 powdered lemonade containers just to get enough HDPE to make my mallet head. It took a number of hours to process it all. I think I watched a full season of Scrubs in the shop.... :)
The handle of the mallet is made from a cherry board and adds a nice warm contrast to the plastic! This mallet packs a punch and is quite heavy given it smaller size!
Thanks for looking!