You need a 4” vice at least. I recommend this one WEN 434TV 4.25-Inch Industrial Strength Benchtop and Drill Press Tilting Angle Vise https://www.amazon.com/dp/B07DB32SBN/ref=cm_sw_r_cp_api_i_MHtCCbY993RMW
In theory you could pack it cold and let it heat up knowing when it’s done with a temp gun or something and all the material would be heated evenly. Might have to get my hands on some