Elon, I know you have plenty of problems that you are solving or have solved.
Welding metal bodies is not necessarily the best way to make rigid bodies anymore. I know some of the pain points for building bodies that are nonmetallic and I have imagined a degradable solution whereas if one material is too expensive or difficult to work with the material below it will solve the problem less well yet will function to solve the materials problems.
That and I have been dreaming of the Mars mission you are currently working on which is excellent.
Firstly you probably want to create a satellite relay for communications and to be problem assist modules in space the satellites can have orbits and move from orbit mesh energy systems always being most optimal because they answer for power flow and failure issues to known and unknown problems. You may also want a satellite ark that has stored seeds and genomic information that you can up-link with if any failures on the ground have occurred.
It would be wise to have some satellites in space that can do work, mamma, the mother of all laser satellites so you can melt the poles with solar-powered lasers energy directed at the Martian poles, which should potentially be domed prior to melting so you can account for the loss of water through a weak atmosphere. Also, a few other robotic satellites to assist in helping to push collisions of orbital bodies that have utilizable materials to be used by indigenous populations.
Archaea and diatomic vats are going to be incredibly important to long term material conversion of percholate soil to more usable organic compounds to ourselves and the ark, the ark being a database with all genomes we have recorded, and a multiplicity of seeds we have taken off world. The more bacteria you have producing useful outcomes the better it’s easy to seed new sources with bacteria brine's and they are the grey goo, ha-ha. The good news is that Martian soils itself could be used with some of these bacteria’s to help to make rocket fuels and other useful byproducts.
The environments should be similar to Michael Reynolds earth ships and environments that incorporate lots of mosses and other flora. The flora will luckily be opportune and have many benefits known and unknown, that’s why we brought over dandelions and earthworms to the new world, so this time we bring dandelions and aloe ;)
Have fun your friend Luminosity