I got the inspriation for this idea from Smack536's tip of the month submission in the tip o the month forum. B)
There are essentially, two materials needed for this project: Plastic canvas (ridgid) from an arts and crafts store and fishing line. Your optional material would be aquarium sealant.
This is a rather easy project if you have a free hour to throw this thing together. This is perfect for people who are utilizing a HOB (hang on back) filter and there is no media basket or bio-wheel.
Basically, you just trace your filter cartridge onto the plastic canvas and cut it out. Then you measure how much of a basket you can fit into the filter and cut out the panels to act as the bottom, front and sides.
Or measure the space you want to fill with the media basket. Any space that is open enough to fit a custom basket into will do, as long as you still allow room for the regular filter cartridge. Unless, of course, you decide to make this thing your actual cartridge and fasten new filter floss to it instead of bothering with rinsing. Anyway, with those numbers (length, heigt, width, depth) you cut it out of the plastic canvas and assemble the panels with fishing line. Tight knots burned flat (with a lighter) at each end of the seams keeps them from unravelling. Or, instead, you can use aquarium sealant on the seams to add some extra durability.
Just think of all the possibilities there are for using this stuff. ANYTHING that has to do with water and flow has a potential place for it. I'm sure this won't be the last one you see either.