Seeking ideas for useful projects in which to practice soldering copper

Homeowner here. I am experienced in working with PVC, CPVC and Pex, however I've always been a bit intimidated by soldering copper. I'd like to change that and plan to get some practice in, but I don't really want to waste a bunch of fittings and copper in doing so. Are there any useful builds/projects that Plumbers assign to apprentices for this purpose?