For those that don't want to pay thru the nose for one of these, I just made one for under $30.00 and about 30 minutes.
I had all the items lying around in the garage except the heater.
14 gauge wire (extension cord)
single gang electrical box
dimmer switch
cartridge heater - 55 watt, (ebay buy)
Aluminum mounting block
Using the dimmer switch set at half, this heated my Lyman 45 to ~ 110 degrees in about 20-30 minutes.
easy and inexpensive ....
Scott