Hey Quadro, promised you to post my solution for the Shuttle Maintenance puzzle, here it is:
Here's the first step: welding the 3 block propulsion units, gathering them in a set of 2 and then splitting them up to fall down at each side of the shuttle. Nothing special here, I guess you'll have a similar setup.
(click for animation)
Step 2: Since the shuttles arrive first I made a blocker stopping the shuttle. As soon as the second propulsion pod drops down an electronic eye is activated, which activates 2 pushers shoving them under the welder. The same sensor also retracts the blocker and the repaired shuttle goes towards delivery point. It's a reasonable compact setup, and the pushers allow for the pods to be dropped in from above without the top welders being in the way.
(click for animation)
Step 3: This was the main problem I had to solve on this level; the shuttles arrive faster then the new propulsion pods take to produce, so they end up back to front on the production line. Since the propulsion pods stick out on the rear you can't let all lined up shuttles just go through the welder continuously, since the rear of the propulsion pods will get welded to the shuttle behind it, welding all shuttles into one solid block.
My solution for this was to use pushers as blockers to keep the shuttles spaced out over the length of the production line. As soon as the first shuttle in line leaves the welding station they retract, as soon as the next shuttle arrives they extend again blocking all shuttles in line simultaneously, looking like this:
(click for animation)
All in all it works pretty good, and my stats are very acceptable; 155-172-95
(for comparison, your stats at the time of this post are: 652-187-126)
Wasn't actually too difficult, although keeping the shuttles spaced out needed some creative thinking. At first I made a system where the next shuttle would be shoved sideways behind a block to keep it on hold, then shoved back on the conveyor when it was their turn, but the current system I have with keeping all pods on hold along the entire length of the supply conveyor works faster and has less footprint as well (though it does use a couple more blocks).
Hoping it's inspiring for when you speed up your solution
