Cables and service not currently available. Sorry.
1) An Official Nintendo Game Boy Micro Game Link Cable.
2) Any Gameboy Advance to Gamecube Link Cable. The directions below show how to use the following link cables:
- Official Nintendo Gamecube to Game Boy Advance Connector Cable
- Nyko CubeLink cable (No longer available)
- MadCatz SystemLink cable (For both GCN & GBA connectivity via the GBM)
3) Soldering skills
Cable Service Information
I offer a cable building service if you do not feel you have the soldering skills necessary to build a cable. Unfortunately I cannot supply the cables myself. For the service you must send me the official Nintendo Gameboy Micro Link Cable and any GC->GBA Link Cable. I charge $20 for the service, which includes return shipping. The final cable will have the electronics enclosed in a small project box, the same box you can see in the photos here. I am sorry but I cannot source the cables for international orders anymore. Send me a Private Message if you are interested.Official Nintendo Gamecube to Game Boy Advance Connector Cable Directions
(My preferred method)
First step is to cut the GameBoy Micro Link Cable next to the connector box, strip the shielding, and strip/tin the wires. Only the RED, BLUE, and ORANGE wires are necessary, along with the ground shield. You should be left with something like this:

Please note that I've only stripped the wires a tiny bit. You'll see why in the next photo.
Now, solder the wires onto the GC->GBA cables as shown, taking great care not to short any pins together. When I do these cables, I connect the ground shield to the left "post" on the circuitboard, then bridge it to pin 6 with some solder as you can see in the photo.

After you've finished this, you can try to stuff it back into the GC connector housing. If you do, be sure to cover your work with electrical tape and provide some strain relief on the cable. I end up using a small project box to enclose the electronics.
Nyko CubeLink Directions
I don't have any fancy pictures for this method but it should be self-explanatory. The completed cable is shown above.
First, cut the GBA end from the Nyko cable and cut one of the two Micro cables at the central "hub". Strip the wires so you can wrap them and make a nice solid connection. The wires link like this:
Nyko Cable -> Micro Cable
Black -> Wire shielding
Orange -> Green
Brown -> Brown
Green -> Orange
Blue -> Red
White -> Blue
Wrap everything up with electrical tape making sure that none of the wires touch another, or use heat-shrink tubing. I wrapped each individual wire with electrical tape and then carefully placed all of them in the shielding that I grabbed from the Nyko cable. I used small zip ties on the cables to decrease the stress on the solder joints in case the cable is pulled. Everything is contained in the shield on the right.
It's been a very long time since I've come across this cable. It's possible that only the RED, BLUE, ORANGE, and ground shielding wires are needed from the GameBoy Micro Link Cable. If I ever run into one of these again, I'll test it and post the results
MadCatz System Link
The rest will be coming soon...
Old method for the Official Nintendo Cable
Thanks to UncleBob for pushing me to start this and CheapyD for locating supplies for the first batch of cables back when I started this.
Edited by Troz1820, 04 September 2009 - 03:02 PM.
Cables are sold out