These are the valve adjusting wrenches that I made. I started with two cheep 14mm wrenches. I cut the box end off the wrenches and bent them then brazed flat stock to them. To make the third wrench I cut 1/4" off a 30mm socket then brazed that to 1/8" flat stock and then cut a 20mm slot in the end.
Hope this helps someone
Total cost was less than $10 and I have been using them for about 2 years with no problems.
Oh yea, you want the two wrenches to nest so that the upper one can pass over the lower one when you are turning them.
I just added some info on the valve spring retainer wrench. With these dimensions and the photo it should make sense.