Well, it's not RF/Wireless related, but there really isn't a big selection regarding controllers for the 3do, especially arcade-type controllers. Even though the controllers available aren't bad, there's one specific problem, connecting each controller to another controller. Connect 8 controllers, and you'll have a web of tangled mess basically.
So, why not build a multi-controller station that connect all controllers to just one port. I'm sure you're wondering how to go around each serial port from each controller and such. Well, you don't. It will take a lot of soldering, but by using an old PC controller hacking method, by taking the controller apart, ripping out the board, cutting it down as small as possible, and then soldering each contact to the correct wire, and each wire to its external connector.
The difference between that method and this one is #1: multiple controllers will be used #2: the serial ports will also be soldered to each other, just as if they would if you were going to hook up the controllers as they are supposed to. So, in essense, even when the homemade controller isn't connected, the 3do will see it as connected.
The boards will be mounted in a radio shack project, with atleast 2 controller ports on each one, if not 4. Then on the side, the last serial connector in the chain would be external, so either another 3do controller could be plugged in, or another project box just like this one, to make it 4 or 8 controller ports.
The controller ports would be DB9 or maybe DB25, depending on how many wires you would need for the buttons. The cord from the first controller in the chain could then be used to connect the box to the 3DO.
Then you just have to build your own arcade controller (With some of the plans on the net, perhaps) and make sure you've got it wired the same way your ports are wired, and you'd be all set. Maybe add a printed/laminated design to the box, to make it look nice.
This kinda reminds me how I built a dual SNES to PC port system out of an old NES game (not system) case, the ones ya usually got when you rented them from blockbuster and such, an old DB25 port that I had taken out of a 386 PC, a printer cable, an SNES port that I had taken out of a broken SNES system, a few strands of wire, and some solder. It was a tight fit and didn't look the best in the world, but it worked great. Apparently, the driver wouldn't run correctly with DX9 with XP. So, when I switched from windows '98 to windows XP, I couldn't use it any more. .
