Patents relevant to this project are:

• Valve: US8241126 (gamepad with swappable analog sticks, trackballs, and trackpad)
• Act Labs: US6279906/CA2293347 A1 (game controller with swappable hardware interface modules to work with different consoles)

Luckily for me, I live in Canada and Valve only has a US patent, so I don't have to worry about that one. Theirs also has some limitations on placement of modules that I don't expect mine will have. The Act Labs patent is a bit more worrisome, but I think I can work around it because its claims are quite specific to the system architecture they chose. As long as I don't have an active adapter module between the controller base unit and the console that is connected to the controller using metal contacts, I should be fine. That rules out the middle option in the diagram, but the radio option should still be fine, and passive adapters with the protocol handled by the controller's processor should also be fine.