An interesting servo-based project is a Micro:bit plant watering system. The project is given in two-parts on the Micro:bit web site, and rather than duplicate their work, I link to the two projects. The first is simply a project to measure soil moisture. The second project builds on this by adding a servo that transfers water to the soil when it is too dry.
If you do not have a pair of nails, you can use two of the long bolts from the MakerCart kit.