I cut felt and then utilize hot glue gun. It works......I also use the felt and glue it with the hot glue gun on the back of all my wall art

I just buy the felt protector stickers at home depot or lowes and peel and attach. Measure the size to get the right ones.

If you have a Costco near you they sell a package of felt protectors in different sizes for a great price.

vinyl or teflon glides like pictured above are the best option. I have seen the felt peel off, and become more of an issue than the smooth metal foot that is on the chair to start with. You may want to make sure that the primary purpose of the metal foot is not to level the piece. Is this a dining or occasional chair? If not, how often will it be moved? What type of wood flooring do you have? You may not need to add anything, if it's a hard wood, and a piece that won't be moved often.

Bed Bath & Beyond have a huge selection of felt pads -- I like the ones you can cut to size so the pads don't show. Good luck!

Best thing to use is the "hammer on" FELT pads with the ring or nail...
Using the glue on pads presents the possibility that they will come off or slide off center.

Lowe's has a great selection as well as finding them on Amazon.com:

http://www.amazon.com/1-Inch-Nail-Round-Felt-Brown/dp/B000PB0ZTA/ref=sr_1_9?ie=UTF8&qid=1405709963&sr=8-9&keywords=floor+protectors+for+furniture+legs

I have the felt peel and stick pads, they work well but they do collect dust. Also they come in tan and brown in my house brown works better, something to think about if you buy them.

I use the felt pads and have to change them often as they collect dog hair. Yuck.