As the vacuumcleaners dustbag fills up it get's slower and slower until it's finaly useless. Dustbags tend to be expensive, single use and at any time the manufacturer could decide to stop making yours, that is if the store still sells them.
Enter the resuable dustbag. It's made from an old T-shirt, a zipper, some vinyl and the piece of board from an original dustbag.

Slight update : This instructable got picked up on Hackaday. I'm so happy! :-)

Step 1: What You'll Need

You'll need ..
a T-shirt or other piece of sufficiently drafty material
a zipper
a peice of soft vinyl, rubber or suchlike
sciscors
sewingmachine or needle and thread
a dustbag that works with your machine

Step 2: Get It Right ..

Cut a piece of the T-shirt big enough to wrap around the old bag.
We'll be using this to sew up a bag sorta like it.

Step 3: Add Zip ..

Sew the zipper onto the fabric so it will close up nicely.

Step 4: Add Vinyl ..

Cut a hole in the vinyl big enough to catch the hose, see original bag.
Add the piece of vinyl to the fabric and sew it on.
Sew up the bag, don't worry about excess fabric, that can be cut away later.

Step 5: Fittings ..

Add the piece of board from the bag (or whatever it is that makes it fit) over the hole in the vinyl.
I managed to sew it on but maybe you will have to glue it on or something, just make sure it's on there.
Don't forget to cut a hole in the bag underneath aswell.

Step 6: Fit It in the Machine ..

Make sure the bag fits inside the machine and everything.
Mine worked first try.

Step 7: Success!!!!

Behold! It's collected the testscraps on my bench. I'm a genius. Now to make a robot slave that can use a vacuumcleaner on the floors and tidy up that mess.

Step 8: Updates

091109I noticed it's over a year since I made this and since I emptied the bag yesterday all I can say is that it's still working great. Haven't had any problems since I made this and never needed to buy another bag.101115I seem to check in on this every year :) The bag is still working well and I haven't noticed any problems with the vacuum cleaner so that's two years on the same bag. Take that, proprietary bags!130520Final update. The vacuum is dead but the bag still works :)