Hi Bill
You are correct, I did not show any details for both the Pressure Gauge and Injector. If you look back to Part 1 in M.E. 4444, you will see I did make reference to both these items which I do make. With regards to injectors I followed the articles by D.Lawrence in M.E. in year 1975. and achieved success. I do make my own Pressure Gauges, I looked on this as a challenge many years ago and have successfully made a number over the years for my own locos and Traction Engine. Both these items are not what you could say easy to make, for this reason most builders purchase them from our suppliers.
For the Pressure gauge, I suggest you go for 1"dia. with a range of 0-150psi. and for the Injector, a No.3 (14oz/min.) is O.K. Hope this is helpful
Cheers
Henry