In memorial I suppose…
2020-01-08 I recently discovered that Clay's Kits has shut down (clayskits.com.) Clay's Kits was a small start-up that manufactured really great breadboard mounts for small single-board computers like Arduino, RPi, and others. I am very sad to hear this news, Mr. Douglass created wonderful things that were extremely well designed and very high quality. He has on more than one occasion helped me personally and was always generous and fair in any commercial transaction. I own several of his products and I am not very happy that I won't be able to purchase more. Here is an example of the fine products he manufactured Clay's Kits Breadboards

The top breadboard mount is for Raspberry Pi, it will fit all models as of this writing. The rightmost is the version for the Intel Galileo Gen 2. The leftmost is the mount for Arduino, and can adapt to fit any model Arduino including the super-sized versions.