[Cartergeneralconstruction]

I'm in the early stages of planning out a shed. I have access to free 2"x3"x10' boards at work. I've been looking around and all i can find are posts about 2x3 vs 2x4 for framing. Most say that using 2x3 is not worth the small savings vs using the strength added by using 2x4. My question is could i double up the 2x3 and have a 4x6? Or even every other stud double it up. I do not plan on finishing the interior wall. The shed will not have electricity or plumbing of any kind. I was thinking The shed would be 10'x20' on a concrete pad. I will be buying treated lumber for any wood that touches the concrete. I haven't bought anything for this project yet fyi.
If it was me I’d frame the 20’ walls with 2x4 and the 10’ with 2x3. Not knowing factors like wall height etc. My advice is 2x3 studs under 8’ on a shed are ok. If you plate the 20’ walls with 2x3 the top plate will be to weak to lift.
If you have enough free 2x3 (and your really cheap) you could plate the walls 2x4 and use double 2x3 stud one flush with inside of wall and the other flush with outside) 24” or 19.2” o.c.
You can find sheathing rated for 24”o.c. Hopefully you know all the other effects 2.5” deep walls will have like R-value , 4-9/16 door jamb will stick out etc....