If he is planning to make it a business, he will need to determine if customers will be coming to your property. There will be lots of things he needs to research if this is his intention. Insurance, licenses, and zoning will be important. Neighborhood associations often prohibit this kind of activity so he needs to start there. For example, I once had an employee who started his own lawn service business. He bought a used truck and trailer and purchased equipment to begin his service. After all that expense, he discovered the HOA would not allow pickup trucks, trailers, or signage. He had to choose between moving to another home or renting space for his truck and equipment.

My husband, a former professional handyman, would like to turn the bay into a home-based all-purpose fixit shop. Any advice

Have your husband ask his own questions.

He prefers i ask. Not a technology guy.

Check your zoning laws. Neighbors may not appreciate a shop opening in a residential neighborhood.

First find out if he can have a business in your area. Then post pics here of the whole plan to scale . IMO he has needs for this that you are not sharing and what kind of fix it business is the first question. What he plans to fix will drive what nhe needs in the space so get him here to give us that info or get him to give you alist

All good points about the zoning, insurance, licenses, etc. Husband was already looking into this. If he cannot run as a business, he will do as a retirement hobby to help neighbors and nonprofits and to continue teaching our kids and grandkids about fixing rather than giving in to a throw-away sociey. Shop is already adequately insulated, heated, lighted, and ventilated. We added the third bay in 2019 for his woodworking but he decided to open himself to more. The purpose of this post is to glean smart ideas (like the mini fridge mentioned by beesneeds) to further trick out the workshop.