It's a little harder to lift one's self up off the floor, but while you are down the chairs are quite comfy.
One can even rock back in them, if you are not afraid of falling over backwards. If you are, you can put a sack or two of sand behind the chair to keep it from falling too far backward. Some chairs have backs that tilt down. Depending on where the balance points of the legs are, they can make great reclining chairs.
Step 1: The Chair Bottom
You have to look for bolt holes, or other irregularities where you can run rope through to hold it in place, or ways to tie the rope to the frame. Rope is cheaper than silicone rubber, so it makes a good fill material. Wrap it tightly, with silicone rubber saturating it as you build it up. You will get a relatively cheap foot that stays in place and is tough, besides being soft and friendly to floors.
Step 2: Build the Feet
The feet are kind of like turbans wound out of rope and saturated with silicone rubber.
Step 3: Falling Over Backwards
To prevent a full tip-over, I stack a couple sacks of sand behind the chair. They make a good chair stop, so I can lean back against them to use the chair like a recliner. A foot stool makes it complete.
Step 4: The Seat Cover
The cloth that covers the bottom tends to slip forward from sitting on it while leaning back. To keep it from slipping forward, I tie small objects such as marbles in bunched up pockets of cloth. The string that ties around their neck ties to contact points near the seat's back hinge points. That prevents the cloth that covers the bottom from sliding forward.
That's all there is to it. It's fairly quick, easy, and cheap. It's also very comfortable.