I have a mosaic made of keyboard keys that I made by gluing the keys to a piece of cardboard. After some time, the cardboard has begun to warp under the weight of the affixed keys.
I now have a similarly shaped piece of plywood that I plan on affixing the keys to so it won't buckle under the weight and will stay flat when I mount it.
My question: What type of glue/adhesive should I use to affix the keys to the plywood?
I originally used tacky glue to affix them to the cardboard and that seemed to work pretty well. Would tacky glue also work in this case? Or should I use something like wood glue?