When I grew up there were only 2x4 walls, studs on 16" centres were standard. That is what I knew of.
Now we have 2x6 walls or 2x4's on 6" sill plates with the staggered 2x4's or even SIP's.
I am interested in other types of designs. Also is it possible to make a SIP at home? What glues are used?

Why you may ask? I would like to build a camper for a 47 Mercury flat deck truck.

 

If I were building a camper body for a '47 truck I wouldn't look at house construction. I would look at aircraft and airstream campers. It's a totally different construction method but it can be done DIY and certainly would be cool especially if you incorporate "roundness" or streamlined as was becoming popular during the period.

As for making your own SIPs. Yes and no. Yes they could be made if you read up on how they are made. It does require some special tooling to contain the wall while the foam is expanding and curing in addition to the foaming equipment. Something I wouldn't consider worth while as a DIY project. If you want to go that route I would have a SIP manufacturer make whatever I wanted.