I think small order runs would be good, as manufacturing is pretty expensive to do small quantities as you run into minimum charges, so prototypes/small quantities, I’m sure there must be quite a big market out there for that.
You could come up with an offer for clients, they only want 2x, you make 4x and advertise it on your website, if sold they get 10% of the price or something.. Have no idea if this is feasable. We are in manufacturing and we keep stock on the shelves for customers, but the problem is sometimes they may not order for 5 years, but if it costs the same to make 5x as it does 2x, it sorta makes sense.
As above, drift sets, crown race tool, custom headtube sleeves, seatpost sleeves, emergency hangers, etc