Starting with JT's plans, I scrounged through my extensive collection of spare parts and leftovers.
I substituted composite decking material for the wooden parts:
+ Does not change shape with changes in humidity
+ Does not require protective paint or coating
- Noticeably heavier than typical woods
- Butt ugly
In place of the 3/4" dowel for the pivot I use a 1/2" polymer roller I stripped from some defunct appliance. Very strong and stable with little rolling friction.
Instead of making attachment points for the dowel, I used 1/2" conduit clamps. Fewer parts, no gluing.
Since my observing locations only vary by about 3 degrees in latitude, I swapped out the 7" 5/16 threaded rod for a 5" hex bolt of the same size.
So far so good. Add some spring tension and try setting it for my latitude.
Now to try putting a scope on it ... oops. A little butt heavy.
So to get the scope upright and get it to balance, I added a 90 degree adapter and a counter-weight.
Now to find the balance point. (Thanks for the tip Kathy!)
For the tripod adapter and low friction pad, I used ordinary furniture sliders and the side from some household cleaning product.
Last minute addition was a two axis bubble level. (Not shown)
So there you have, "The Mark I"