Yantras are geometric designs that are designed to change awareness. One use is for meditation. There are many different yantras available, and any of them are suitable for meditation. Click here for details of how to meditate on a yantra.
On this page there are three yantras that you can download and print to use for meditation. You can get a plastic stand for them at most office supply stores.
Each yantra has a jpeg version and a Photoshop version. NOTE: the JPEG and Photoshop files are quite large.