Apologies to anyone who was already aware of this, but I’ve just come across SBB’s luggage forwarding service, and it seems like really good value.
The canny use case here is if you have a few days travelling through Switzerland, and don’t need your bag. The basic service is very reasonably priced: 12 CHF for ‘Station to Station’ delivery. It’s relatively slow (drop your bag off on Day 1, pick it up on Day 3), but I think that can work to your advantage when you think of it as luggage storage and transport together.
They will also store the bag at the destination station for free for 4 days.
https://www.sbb.ch/en/tickets-offers/reservation-luggage/checking-taking-luggage.html
There are also more expensive door to door and Express options, but the basic service is the one I could see myself using.