After building your microscope, you now hold the power to look at very small organisms and non-living samples. Here are some ideas for sample slides you can create and image.
Elodea densa is a multicellular plant you can use to image plant cells. A slide can be constructed by taking a leaf and placing it on a microscope slide, then covering the sample with glycerol and a coverslip. To keep the sample from shifting, you should line the exterior edge of the coverslip with nail polish.