Yes, I make things to sell. Mostly high-end custom work. In our shop, over the last 18 years, I have designed, fab'd and welded about 99% of what has went out the door. Most of which has been for the marine industry. I also have an industrial scale welding rig installed at my home.
All of the welders in our shop are young men I taught from the beginning. They are all very good welders now. At least with our use of it. I went to school for it full time for 18 months initially. In all of my other trades, it was the missing, specialized ingredient. I ended up going to school over a clutch pedal I needed welded. Took me all day to find someone to fill in the linkage hole that had time to get to it. Took them 10 seconds to repair it. Metal fab was always a part of my other jobs, though.
Yes, I have repaired a boat prop but it takes specialized equipment to balance and set the pitch. We typically farm that out to experts that specialize in that. They can also do it cheaper than we can.
All of the young men I have taught to weld, including both of my sons, will tell you it is the toughest thing they have ever learned to do consistently well. And they have had what would be considered intense practice, all day, every day. My youngest son has managed to duke some 10-20 year hires we had briefly. Half of why they quit, or got run off, is because they could not take the fact that cubs were kicking their asses.
This is what I mostly built for the last 25 years was boat tops, towers and other furniture. Mostly anodized pipe and flat stock.
But, I also filled in between welding/repairing things such as these swivel fittings and such for the petro industry. These are for gasoline pipes that they fill the tankers with. I've also built fuel tanks and a bunch of other hardware for the racing industry, sewage treatment plants, you name it, I have likely welded it at least once.
For fun, here is a cart I tricked out for a customer.