Trio Block Adapters and Pieces

My son has some building block toys that haven't been made in a while. He's gotten quite a bit of mileage out of them considering their simplicity and that he's had them since he was only a couple years old. I suppose they appeal to his inner "Minecraft". I got the idea to create different variants of the existing blocks to help him create new and fun things with the original blocks. All pieces work with the factory-made blocks well, and can be used to make many fun things. He likes to create bl