I’m making my kiddo a couple serving trays for shuttling stuff from the kitchen to the patio. They’re designed to nest and the smaller of the two will feature an “egg crate” insert to help keep beverages stable. I’m planning on using interlocking slats inside a frame. Think jewelry box dividers only scaled up. Can anyone suggest a source for a primer on making something like this? I just want to get my head wrapped around it prior to diving in.