The heat gun/sifter approach has been around for quite awhile, just put my own spin on it to give me very consistent results, infinite adjustability, ability to roast outdoors year round (temps from the 90s down to single digits at times), be very safe in the process and simple to keep clean. Also didn't want the nanny/safety mechanisms that some companies use on purpose built roasters and building it myself saved quite a bit of $ for what it does as well as the expected longevity. Granted some like to roast more volume less often, but I take the opposite approach and roast in 200 gram batches very often. The way I rotate green/roasted and consume only for espresso it works out perfectly. Get insane consistency batch-batch and nothing ever sits around more than ~10 days post roast.
After having used several quality 90 degree type heat guns with great results I decided to go all in on the Steinel straight design due to the brushless motor (very long life) as well as a quick/replaceable heat element if it eventually gives out. The sifter and all components are stainless to keep things as 'food grade' as possible. I have temp probes in various ideal spots to give very consistent feedback relatively quickly. The hot air tool has a rather precise digital temp readout then I have one probe right over the tool nozzle, one catching a reading at the sifter screen for an idea of how much heat is hitting the bean center mass and another one submerged in the bean mass as it's being agitated. That's where most roasters miss out on temp feedback and rather important as temp changes happen faster than your senses can pick up with sight/smell. The sifter is rotated by a Milwaukee 12v right angle drill held in place with a neodymium magnet for quick disconnect.
I always roast outdoors due to smoke/chaff and use an EGO 650 blower for quick cleanup as well as to rapidly cool the coffee at the end of each batch. I keep the blower very clean and it's a fantastic way to cool coffee and keep the roaster in great overall shape as roasting can get a bit messy with the green dust, chaff, etc. All said and done I can roast exactly what I like when I need it and don't have to spend time ordering/waiting for roasted coffee like I once did. Also saving around 50% in cost doing it myself and find what I roast to easily be on par with the best I ever bought from any commercial artisan roaster nationwide.