I was just googling roller workouts (just got a set) and saw this interesting quote:

"Two poker cards stuck in your spokes will give as much resistance as most people can handle when riding rollers."
https://www.ultracycling.com/training...ing_part2.html

I haven't tried it (I currently get enough resistance with big gears on my TravelTrac) but I may in the near future.

Anyone tried this or some other homegrown solution for adding resistance to a trainer which doesn't have a pricey fan or adjustable resistance device?

let some air out of your tires.

Air out of tires or towels on the ground are the two i've heard of.

Never heard of those methods but I run low tire pressure. I'd be interested in hearing some other techniques.

Put towels on the floor so that the drums run across them, creates added resistance.

Costs nothing.