This is my first instructable. I looked at all the usb key mods I could find and thought I would give it a try. My goal was to make something durable and useful enough to put on my keychain. I ended up combining an old VW flip key with built-in transmitter (cool in itself) with my own key and a 1gb usb key.
Step 1: Get the Parts Together.
The transmitter comes apart easily. Once open, remove the components and discard. Next remove the old car key. Use a small nail or paper clip to remove the lock pin that holds it in place. I took the key I wanted to replace it with and cut it down with a hacksaw blade to a rough shape. Then I put it on my bench grinder until it was the same shape as the original VW key. I used a Dremel tool and the hacksaw put a small notch in just the right place to accept the lock pin. Insert the new key and lock it in place with the pin. This took about 10 minutes of trial-and-error...it's really not too hard.
Step 2: Make Room for the Usb
My first thought was to replace the actual key with a flip out usb key. But, after looking at the sizes of everything I had, I decided to keep it simple. Plus adding my house key would make it more useful to me. The keys are easily interchanged if you later decide to use your vehicle key, etc.
I used my Dremel again to cut out a notch for the usb connector and to remove the plastic molds for the battery and circuit. I removed the purple case from my usb and wrapped some electrical tape around the circuit. It may be better to leave it open since the board heats up. I'm not sure, so leave a comment if you have suggestions. Once the space is cleared out, the usb slides in easily. A little hotglue secures it in place.
Step 3: Put It All Together.
Once you have everything in place, it should go back together easily....don't force it. I wanted to include the LED light to shine a beam in line with the key when flipped out. I haven't done this yet because I'm not sure if I can drill into the space without ruining the flipping mechanism. I figured sometimes you just have to know when to stop.
I hope you like my first entry. I have more that I plan on uploading soon. Thanks for your comments.