ive dabbled with bho for a while and was getting tired of the butane and 3 day plus purges to get it clean. I wanted to try rosin but didn't want to buckle down on a 500+ rosin press. I went online and bought a 90$ A frame 6 ton press. To heat the plates that came with it I stuck them in the oven until they got to 230 and took them out and when they cooled to 200 degrees I gave it the squeeze. I used a 1/8 of some homegrown and got about a 15% return. The plates it comes with suck because their cast and have dimples on the face. Those dimples allow rosin to collect and stay on the puck, hiding in the dimples. Once I get completely flat plates and finess my technique a bit im sure on 20+% returns. I'm about to put the squeeze on a lot of bud
Yea i would recommend just building your own press. They have some rather simple designs on youtube but cost effective. Much like led lights some research and diy videos can save you quite bit of money.
Yea I'm going to try to sand to smooth them. Ultimately I plan on buying aluminum plates to put a heating element inside
Most presses use cast iron plates that are heavy and hold a lot of heat mass. Aluminum is the opposite. It also bends easy. I'm sure you have a good plan but something to consider. Your method heating them up seems pretty sound.