T-bolts can be found in the plumbing supply stores or big box stores. They are used to secure Toilets to the pipe flange and have oval heads. Wing nuts from the hardware section are also readily available. Some Lowes stores also carry the black plastic wing knobs that are commonly used by woodworkers for building fixtures, but they don't carry them in any quantity. I usually buy these from a woodworking supply.
I have feather boards that were made from oak, maple, poplar, pine, 2X4 scraps, etc. Almost any solid wood will do fine. Those made from composites and plywood won't hold up long. The feather board's design, size, slot spacing, overall length, and finger length all vary depending on the purpose that I built them for. I also have a few of the purchased models that are made from plastic, but I prefer to use my wooden ones, as they seem to do a better job.