Liked Michael's assembly option ideas! If you did 7 individual ones the shop elves could get a new 7 sided toolbox (the un-used crankcase if 7 single engines were made)   

... new toolbox... to store the tools they took from ME!   

I got the flask parts made for use molding both the aluminum pattern halves, and the complete fuel tank.

In the photo, the runners will be in the drag, and the pattern will be in the cope.
I have it laid out on the table inverted just to show the pieces.

I am gambling on a 1.25" diameter straight sprue, and plan on filling very fast.
Once the metal rises to the gates, the sprue should remain full.
I want as fast a fill as possible with iron, so that it does not have time to cool off and cause a partial fill.

Everything is oversized for the aluminum pattern half pour, but I think it will still work.

I happened across the flast joint design somewhat by accident when trying out the dado blades.
The joint happens to close on the inside of the flask, and the rounded cut on the outside of the flask does not matter, other than it allows the flask to hinge open in a shap-flask fashion.
One corner of the flask will be glued, and the other joints will hinge.
Removing the flask before pouring metal eliminates any possibility of the flask being damaged by spilled metal.
I have 1/2" and 1" spacers that I insert against the fence, to make the cuts.
I could make a spacer guide, but the wood inserts are very simple and work well.

One of the taller and the shortest flasks will be used for the pattern half molding, and the two taller flasks will be used for the complete fuel tank mold.

If this runner/gate layout works, I will pour it in aluminum.
For the water hopper, I 3D printed the runner/gate arrangement.

I am inching closer to casting a permanent aluminum pattern half, and if that works correctly, then I will pour a complete fuel tank.
It this proof-of-concept layout works well, then I will use some variant of it on the remaining parts.

We are getting close to tea time.
.

You can still decide whether to build one engine or seven individual steam engines 😁. Or just one engine with an excellent supply of spare parts.......

Good work 👍

The CAM program allows over-cutting of a profile so I can enlarge the gap as needed.  I considered scaling but this was easier.

With the deep heads on the hand made bolts, and the general style , and much use of brass, I would think that this engine is quite considerably old, going back to the time that Model Engineer Magazine very first appeared - late Victorian era? Dave

Oh wow really I did notice the bolts are strange, the heads are very long unlike anything I've seen before.

Good news though, after a few hours of messing around with both eccentrics we have a running engine in both directions! Definitely could do with the timing tweaking and try and ignore the flywheel motion when you watch the video! 

https://youtube.com/shorts/6D0SZ5J13ho?feature=share