electrical problems with the heater element.
Those draw a huge amount of power and thus may need some more than just an ordinary wall socket.
And you should keep the regulator too. Finding another poti that can handle that beast may be hard
thermal problems.
be sure to have enough air around the heater to not get burnt by accident while preheating the thermoplast.
The less elegant but pretty safe idea I saw (i guess on instructables.com)
was heating the thermoplast in the oven and then applying it manually to the vacuumformer.
(wich was nothing but a box with holes and vacuum cleaner )
All you have to make then is a box and a steel frame with detachable handle.
'sid