St tropez still do their manual tan. Ellisons stock it.
Basically you do a face and body exfoliation then rinse it off (or put them in the shower), moisture the dry areas then massage in the self tanning lotion (wearing gloves). Let it dry a bit and buff up the guide colour so it looks even to go home in.
This is what we all did before spray tans were invented!
It actually makes a nice massage type body treatment for the client.
I think it lasts longer than a spray tan personally and good for clients with respiratory issues worried about the fine spray.
St tropez used to have a video on their website on how to do it. Back in the day, a trainer came to our salon to teach the routine to all to us.
I still wonder if I should offer it again but not sure of the uptake.