One project idea for a welding class is for each welder or small group of welders to work together on a sculpture. Just what the sculpture should be or what it should look like can be decided by the teacher or left up to the students. In large part though, it will probably depend on what materials you have available to make the sculpture out of. If you have a cast of metal junk, you could easily make small statues out of shovel heads, old gears and some broken metal shafts. Let students get creative with their projects, and you might get some strange results.
The propellers on a boat may move the vessel forward, but they also pose a threat to swimmers and to marine life who come too close. One metal working project that a welding class can work on is to create a prop guard. A prop guard is a metal cage that goes around the propeller and it stops outside sources from getting too close to the spinning propeller. Measurements have to be made for the boat, and students will have to choose whether or not to make the cage rounded or angled. This project can prove to be a challenge to both engineer and actually put together.
To work on fine welding control, or to learn to work with smaller welding tools, you can assign students the job of creating jewelry. It's a good idea to let the students get creative but to have them run all of their ideas past the teacher to be sure that they're sound and safe. Students could make all sorts of things: a pin closure bracelet out of steel plates and a set of door hinges, a necklace drop in the shape of the sun made out of a large copper ball with metal spokes, or even a belt buckle with a word written on it in welded screws and bolts.