Hi Salkehatchie,
I built several locks from both Kevin Blackley and TRS. Attached are photos of a TRS type 1 English lock that I built. They were mostly converted snaphaunces. The images show the basic components. On a snaphaunce you add a two-part sear (primary and secondary), a push rod connecting the tumbler to the pan cover, and separate pan cover and steel (or battery). I think a snaphaunce or early English lock would be a good choice for a first-time build from Blackley's or TRS's parts sets. They are large and the parts generally have lots of extra metal with which to work. Both companies make good products. Kevin offers choices with respect to the steel used. He will cast in mild or high carbon steel. The mild steel is very easy to work and fit but it must be pack hardened. The higher carbon steel can be through hardened just by heating and quenching. TRS parts generally can be through hardened if desired. Keep in mind, however, they offer part sets, not kits. There usually are no instructions and I usually make my own springs and screws for historical accuracy and function. Finally, both companies take infernally long times to ship your parts. In the case of TRS, call to find out if the parts are in stock, otherwise you may wait a year or more for them. Likewise, e-mail or call Kevin Blackley to determine availability before ordering.
dave