Sorry, I didn't understand the question. I am making a little ttrpg myself. I used to play Battletech back in the day and I always found the mecha genre flawed by really complicated rules. I want to do a minimalistic ruleset in 3-4 pages (it helps as well for people reading it easier than a 150 pages one XD).
When it comes to art, I usually draw some doodles myself or use stock art. This one here is a lot of images for free. Or here.