This one is much smaller, but planning was the lifeblood of it. 1.31 build, assembled in mars orbit with no cheats (we didn't have any...) and no refuelling (that neither...) And all I used for transporting the parts between planets was this:
View attachment 5429
X2
And this assembled it:
View attachment 5430
X4.
The shuttles only travelled from LEO to LMO and back repeatedly, picking up parts from LEO that was sent up with simple rockets. Oh, and auxiliary boosters (because no refuelling...)
Here's the IPO in all her glory:
View attachment 5431
Older members might remember her... She's still in orbit
...