Here's a video that shows whats known as a Wendy filter, a DIY filter popular with turtle keeps but can be adapted. You also use your pump and pump water up and into some sort of trough full of bio media (BBQ lava rock, pot scrubbers, etc to keep it fully DIY) and make a basic kind of reverse wet/dry filter instead.
If you're intent on DIY, there are options. The first thing it test though is how powerful your pump is going up 2 feet. If possible, take the pump, rig up some tubing, 2 90 degree elbows into another container that you know the size of, eg, 1gal pail or something then time how long it takes to fill up 1gal of water pumped at the height your filter would be at. Then you'll get an idea on how much flow your filter would get it and if your pump is capable of pumping a decent amount of water at that head height.