I've ordered the Dispensor labels for my TR Rewind but I also wanted to add the tops of these to these Any suggestions on getting a clean cut through the solid plastic of the can? An Exacto knife can only do so much.
You could try heating the knife. Otherwise just keep scoring little by little. It will be time consuming, but unless you want to hack them off with a Dremel it's going to take some time.
Take a super sharp, fresh Xacto knife and roll the piece on a table or cutting mat. As you roll, press into it with the blade so it scores the plastic. Keep doping this. The can will eventually either pop apart or be able to be snapped in half. I do this with styrene rods all the time. It's the only way to get a purely flush cut.