First, I cannot find my "before" picture. I know I took one, and I know I've seen it, but I don't know where I filed it, so this one is as close as I could find (mine was in about the same sad shape, but the supports were white rather than red). When I track it down, I'll replace the picture.
I picked up 2 Cosco step stools at a yard sale for $1 each, one was more modern and in great shape, the other one, it had been well-used and but not well cared for--but it reminded me of one from my grandma's house (although hers had a seat that flipped up). So, I brought them home.
First some washing with water and dish soap to get rid of the grime and spider webs.
Next, some steel wool and WD-40 on the rust spots on the chrome.
Next, some more steel wool on the painted sections to get rid of the rust.
I took off the old vinyl and kept it as a pattern for the new vinyl (the wool batting seemed just fine, so I kept that).
I took out all the screws/bolts so that I could prime and spray paint all the white pieces without having to worry about getting paint on the chrome or seat. I used a couple coats of gray primer, then 2 coats of Rustoleum white enamel spray paint.
Replacing the vinyl on the chair back turned out to be very easy (I found the sparkly red vinyl at JoAnne's in the Red Tag area on sale for $5 a yard, and I only bought 1/2 yard and didn't use all of it). I laid the old seat back on the new vinyl and cut out a football/oval shape with plenty of extra around the edge. The seat back had sharp hooks on the back to grab the vinyl, so just pull it tight (do opposite sides, then move to another set of sides, etc...until you've done the whole thing).
The vinyl on the seat was tricker. It didn't have the hooks, so I ended up using hot glue to get the vinyl to stay in place until I could connect it back to the seat support. Worked great.
Putting it all back together probably would have gone better with an extra set of hands, but I managed by using my head and shoulders and a fair amount of balance to get it done. Ta-da!