As my slave will be naked as much as possible I thought it would make sense for him to work nude also. He will be getting used to doing domestic work and decorating in the nude and so why not get him to work nude for other males and get paid for it.
Decorating: painting walls, ceilings, woodwork, hanging wallpaper after doing the prep work.
Cleaning: this makes sense as he is a slave and does the housework clothes free. I am sure other men will pay to watch a willing slave do their house work.
Gardening: this is a possibility, but essentially warm summer days if he is to do this nude, otherwise his overalls will suffice
Waiter: I am sure there will be men out there who would like a slave wait on them, serving drinks and meals, whether informally or formally.
I have been giving thought to this and my slave agrees to being so used. He will be advertised offering these services in the gay press, naturist press and even eBay!