So, my issue with the coroplast is that I still have to use chopsticks shoved down the corrugation to keep the rollers from flattening it. At least when sending seeds in them. Just seems easier to sandwich them between the 2 sticks in some chipboard.
Those slats look decent @PatioMat , but I can get chopsticks free. And I’m betting they weight less than those too. Also I’m a woodworker, but routing/ cutting a slot in wash of those sounds like too much work too. Just trying to keep it simple and functional. I’m hoping for the parts to be stuff everyone can access. I still love the brainstorming going on though.