I do my heat gun (HG) roasting in a fry basket, which is nestled inside of an aluminum rice cooker pan, which is in turn in a large stainless mixing bowl - I put the big bowl in my lap and the small amount of contact between the two bowls insulates my legs from the heat of the roasting.
I use a Masters Appliance ProHeat 1100 heat gun. I would use a brand new heat gun, not one that was previously used for glues, paint stripping, or who knows what else. Heat guns are available in different heat ranges - make sure yours can make it to the higher temps required for roasting, and can push some air.
Instead of stirring during the roast, I flip the handle of the fry basket to agitate the beans. I work on a rhythm of flip flip flip, then rest while moving the heat gun in a circle around the basket.
I used to just move the basket over a fan for cooling, shaking the beans over the fan, but I've built a better bean cooler that sucks air through - it is made from a large diameter rack fan mounted behind a percolator basket.
