I do electronics & firmware consulting work as well as my small industrial electronics manufacturing business through an LLC. But it really wasn't primarily for liability protection (as if!). I was filling out a Vendor Qualification form to do business with a large corporation and one of the checkboxes was business type. I was checking off Sole Proprietor and then it occurred to me that being a sole prop. might make it harder to do business with big companies, so I formed an LLC the next day.

Don't take/plan to take investment and probably never would unless it was for a specific short-term opportunity.