Old mountain woman if getting one get 2 or 3 40 foot containers so you can use as shop frame as weLl just make a gravel floor if you can’t do a concrete one. Two is parallel 3 is u shaped make sure you Dont make the door blocked in on bottom of u trailer without cutting doors off first trying after is a huge mess and doors won’t be able to be repurposed (make awesome security doors)
Ithe roof when you put it on allow a 18 inch gap between top of container and start of roof, put a clear plastic green house material that looks wavey like corrigated metal sheets it allows light into barn area to reduce lighting needs. Should face the open part of a u shaped building south if possible, it gives you maximum natural light. Keeping the gap between trailers at 30 feet you can get single span pre done roofing trusses delivered and installed in a day, payin is easier and faster unless you have the equipment and skills.
Find a local roofing company and ask them if they sell old job materials, they will say no mostly but then ask the guys, offer them beer for the materials , you would be amazed at what a few cases of beer can buy. I got an arena roof 200 x100 foot roof used stacked on pallets for 10 cases of beer. Delivered to my farm.
Shop around for containers prices vary and inspect them first, make sure the Maine corners are square tube not flat bar and the floors don’t have all the screw popped, check for smells, be wary of almond smell and of petrochemical smell. Almonds scent can be cyanide.
You should never bury containers without renforcement with rebar and cement they tend to collapse. Without insulating the container (close cell spray foam) they get hot in summer and cold in winter so make sure items inside can with stand that, also haveing disilica humidity absorbers is a good idea.
Containers come in 8x8x40 aND high cube 9.6x8x40, if you are building a home make sure you get all the same brand on containers or you will have to dwalk with minor variances but very time consuming with flooring and walls.