30" Door Sweeps

buy a 36" and cut it.

I had to put a sweep on a 32" door. Just bought a longer one and cut it with a fine tooth blade. Came out fine.

All you are going to find at big box hardware stores are 3-0 doorsweeps. You just pick the style/color you want and cut it the length you need. Small saw, utility knife, heavy shears, nothing difficult. Bigger issue is what you use to attach it to the door, exterior rated screws and a thin layer of silicone adhesive works best if you use the u-shape sweep.

My sweep is plastic, white door and white sweep. It fit so snug I didn't even have to screw into the door.

As others have said...with shears or hacksaw.