Here are a few ideas if you are looking for a unique betta tank design. Most of these posts have a link to instructions on how to build them. If you're designing a betta tank on your own, try to keep it on the larger side, and always remember to include a lid in your set up. Betta's are excellent jumpers and we want them to stay in their tanks, not on the floor!
1. Framed Fish Tank
I stumbled upon this idea and thought it was really neat. instructions on how to make it can be found here. I would love to take this idea one step further and have a hole in the wall approximately the size of the fish tank, and set the fish tank in there so the tank sits "on the wall" like a picture.
2. Gumball Machine Betta Tank
3. Coffee Pot Betta Tank
4. Betta Hydroponics
Why not combine a love of fishkeeping with a love of growing plants? A hydroponic set up allows for the plants to help clean the water, improving the well being of your betta. The waste from the betta will also allow the plants to flourish. The image pictured is a product made by Back to the Roots, but it wouldn't be that difficult to design you're own.
5. Computer Aquarium
Those old Macs aren't of much use any more, but you can modify it into a fantastic Betta tank. You could do this with TV's or any other kind of older monitor as well! Here is a gallery with a few different angles of the picture shown.
Have any unique DIY betta tank ideas of your own? Feel free to post them in the comments! If you have a link to the DIY step-by-step, that is more than welcome as well.