I got some plywood at the local Menards store and cut them into 12X20 inch pieces. Some of them are fine but some of them are really warped! Here’s the solution I came up with.
I bought some small wall anchors, screws, and washers. I tapped them into the corner holes, put the wood down, then gently screwed the screws in to hold the wood down. They work great! I just leave them in but they can easily be moved to hold down any size of wood. Here’s a couple photos to show what I’m talking about.
Yep, I actually have a bunch of them printed and they work well. However, I’ve had wood warped to the point that it pops those hold-down pins right out of the honey comb!
Magnets are your friend here too. I cut a lot of non-proof grade plywood and while I’ve used a TON of the bed hold down pins (I owe that forger a BEER!) I’ve also found rare earth magnets are a necessity when doing a full sheet because you can’t use the pins in the middle and as it cuts it will tend to warp up with the cut.
I forget the post, but some awesome forger here put out a 3D printed magnet holder - I had my son print off a set of 6 of those and got the magnets for it - works AWESOME!