I made my own "free motion" rollers today. They are basically bike rollers that mimic real world movements on a bike. Normal stationary bike rollers are easy enough to learn (you use balance, steering corrections ,and gyroscopic effect to keep you up), but free motion rollers are a lot more natural and forgiving.
I was planning on just spending money and buying the real versions, but was weary of spending like $800 (or a little less if I bought them used) when there were so many DIY instructions on the internet that would essentially cost less than $50 for the materials. Plus its fun making your own stuff.
the best part was finding wheels for the project. you ideally use skateboard or rollerblade wheels. I didn't realize that craiglist has has so many cheap assed listings for people selling their rollerblades. I bought them off a dude for $20. They guy I bought them from was pretty manly (maybe a hockey player) which goes against the stereotype of the typical male NYC rollerblade user I had in mind.
The irony i guess is that I was in a hurry to finish the bike roller project (which is basically a bike treadmill to avoid training in bad weather) so I could actually get in a real ride outside today. It was fucking beautiful outside today.