Here's a simple kit where you 3D print the mouse and assemble it. Maybe too simple for what you're looking for, but nice and tangible: https://us.store.bambula

Here's a simple kit where you 3D print the mouse and assemble it. Maybe too simple for what you're looking for, but nice and tangible: https://us.store.bambulab.com/products/wireless-mouse-components-kit-002 https://us.store.bambulab.com/products/wireless-mouse-compon...