Joey (the King of DIY aquariums) has a YouTube Video on making a do-it-yourself pipe canister filter. His was about four-foot-long and made from a 4-inch pipe. This will give you about 2.6 gallons or 10 liters of room for media. Leaks can be a huge problem with Joey’s design (or any DIY canister design).
If one wants to make Joey’s DIY pipe canister design, go to a four to ten-foot length of 6-inch PVC drain pipe with two clean-outs at both ends. For only twice the cost you will get about four to ten times the volume of biomedia of Joey’s design. If you pack such a design with a good media like K1 or pot scrubbers it will do a spectacular job on even a very overstocked large aquarium.
Joey and some others have other YouTube videos on making DIY canister filters from buckets and beverage coolers. Try them if you are the handyman type. They are very prone to leaks as it is difficult to get a good seal with a bucket top.
It is much easier to make DIY sumps than DIY canisters and sumps are much better filters. Sumps also can be made leakproof (with the proper design). So why one would go to the bother of making a DIY canister? For more on sumps see this link
8.6.6. Do it Yourself Sumps
Source: Aquariumscience.org – David Bogert