The hole positions for the T nuts need to the transferred to the inboard piece so the bolts can come through from the body. I aligned the center ply and the inboard piece and then transferred the exact spot for the bolts by threaded a bolt down through the t nut until it dimples the piece underneath. It's useful to get really good alignment here because later you'll bolting the legs onto the droid and if the shaft for the bolt is a little bit cockeyed, it'll be hard to get the bolt threaded.
Then I drilled those holes out with a 7/16" bit. The bolts will be 3/8". This will allow a little wiggle room. Some blow out on the holes is inevitable. Put a scrap piece of plywood on the other side from where you are drilling and drill down into it to minimize it.
Now these two pieces are ready to be glued. Put some screws (I use cheap and readily available dry wall screws for just about everything) through from the inner piece to the outer. Again, make sure they aren't long enough to go through. And countersink the heads so they don't interfere with the gluing.
Add screws all the way down to align the boards during gluing and strengthen the joint.
Get a good wood glue. This stuff is overkill--no need for waterproofing. But I've got a full bottle, so it's what I'm using.
Put a liberal amount on the areas to be glued on both surfaces and spread it as evenly as possible. Once it's on there, try to get the piece bonded together as soon as possible. Once they're together, try not to shift them around any because that will weaken the bond. Put the screws back in to start binding them together, and then add clamps with scraps sandwiching the pieces being glued. The scrap pieces distribute the clamp pressure and prevent the work piece from getting marred. You don't want these to be deadly tight. Clamp them too tight and you'll just starve the joint of glue by squeezing it all out. Some ooze is good. That means you got the right amount.