The great thing besides how versatile the didj is for hacking is it's value as a teaching tool. Sorry to all you hackers this may not prove to be very useful to you, unless you still use carts when hacking a didj.
The drawback to the didj is that the games are a small form factor. I guess leapfrog's response to that is to package them in custom formed DVD cases. When we go out and my son wants to bring a couple games neither he nor I want to be dragging around DVD sized boxes with little game carts in them just so he doesn't get bored with one game and want to play another.
Sure we could buy a bag or something similar that he can bring with him, but why complicate things? This morning was the last straw. He had taken his didj to bed and brought an extra cart with him. But during the night he lost one of the carts. It was easily found but I decided for those times when he's not bringing the boxes and is only going to bring an extra game a small pouch on the back would suffice.
Step 1: Gather Your Gear
For my pouch I sourced a mylar like bag that was afixed to a bottle of colorflame citronella oil.
The bag held the special wick that is needed for the colorflame oil. The pouch is just slightly longer than the game cart so this is a good fit.
Now I realize unless you actually have a colorflame bottle with the little wick bag these directions will be...well, not too terribly helpful. But I'll walk you through what I did, and it should give you an idea of how to work out your own. You'll have to source your own small bag/envelope/etc to use.
One option might be to create a pouch from a fedex envelope.
Step 2: Making and Affixing the Pouch
To start off, I cut off the top of the wick bag. The next step was to insert the cart into the bag to get an idea of how to form the pouch and flap. Unfortunately the bag was not wide enough for the cart to sit sideways. So it will have to go in lengthwise. Pushing the cart all the way down into the bag I then took scissors and cut along the seams of the bag from the top to the edge of the cart. Then cut one side of the bag off. This left a flap that can be folded over the opening of the bag and will keep the cart from falling out.
Once the flap was exposed, I cut diagonally from the bottom of the flap to the top creating a taper. The original idea was to tuck the flap into the pouch with the cart. This didn't work out so well. Upon random shaking and bouncing the flap would pop open allowing the cart of fall out if the didj were inverted. Besides the more I thought about it I figured my 5yr old wasn't going to take the time to tuck the flap in. So I needed an easier solution.
Double sided tape to the rescue. I love this stuff. It's a toss up between duct tape and double sided tape as to which I love more. I've been known to wrap gifts in double sided tape just for the "tapeless effect". It's so much fun, but most people don't notice, so it's usually a waste of time, but those that do it's completely worth it. Anyway, back to the 'ible.
So now we apply tape to the same side of the pouch as the flap but nearer to the bottom of the pouch. Plus a small square of double sided tape at the top of the flap so that when the flap is folded over it holds in place.
Once the pouch is properly taped attach it to the didj.
Step 3: Final Thoughts
At this time my son only has two games so this solution works for now. When he gets another game I'm considering making a second pouch and arranging them so that the cart sits horizontally. This will give me the space to put a second pouch above the first one.
I have also considered velcro to replace the double sided tape on the flap. Since the double sided tape won't retain it's stickiness forever.
Lastly, as usual I make something like this without consideration that I might want to make an instructable. So I never have actual photos of the build process. So..... sorry for that.