I did it! I created a homemade Swiffer. Well, I reused the plastic part, but instead of buying more sheets that can be expensive and terrible for the landfill, I sewed together pieces of vibrant colored fleece that can slip on to the existing "broom". I am currently an owner of a Swiffer and an Omop (the Method version, which is actually very earth-friendly).
Step 1: Measure your Swiffer.
Make sure when you measure the Swiffer (or Omop), you leave about a half-inch diamater free for the stitching. You will need some material to "give" so when you slip it on the Swiffer, there's enough room for the fit.
Step 2: Measure and cut your fleece.
Use fleece. I'm sure other materials will pick up, too (anything will when you drag it on the floor), but fleece is nice.
You will need to cut two smaller rectangles that will go over the top of the Swiffer. Make sure the pieces are short enough to slide over the top. If they're too long, you will begin to stretch the stitching.
Step 3: Sew pieces together
Step 4: Repeat the steps and enjoy your homemade Swiffer covers (you will need to wash them ever-so-often).
Here is the homemade Swiffer on the Omop.
I know...they're a little sloppy, but I'm just learning how to work a sewing machine.