There are a couple ways that you could do this.
First would be to brows the
gobo catalogs of the major manufacturers and see if they have one. If there is nothing that meets your needs, you can design custom glass gobos. This will be a pricey adventure, but it can be very cool. The caveat is that you have to make sue that you choose artwork that is in the public domain, or that you have a license to use. I am not sure where Chagall's work falls. Once you have the artwork, you would
send it, along with an order through your dealer of choice and they will get one of the manufacturers to make the gobos for you.
Another option is to use a
Rosco Image Pro and print your own artwork. This may only be cost effective if you already own one, or if you can rent or borrow one. If you have to buy your own, it may be cheaper to do a custom
gobo. Basically, the
image pro uses heat resistant
transparency that you can print your graphics on and then it drops in the accessory slot of a Source 4 and has a fan to help keep the
transparency from burning. They are great if you do a lot of custom images for short amounts of time. If you need to project your
image for extended periods of time, you will likely need to replace it often. The
image quality is decent, but probably not a great as a custom
gobo.
If your school has any bright video projectors, you could do this as a video projection. You would just be displaying a static slide, but the idea is the same. In this case, all you would need is a computer and the
projector, all of which you may be able to get from your school. For a simple single projection, you could probably just use
powerpoint to create the slides. If you were getting into complex or multiple projections, using software like Q-Lab would probably be better.