A plastic shield would be great, but I don't know where or how you'd get those made cheaply and in small quantities. 3D printing is cool for novelties, but probably too slow and expensive for something like this. Any suggestions for a source?

I was thinking maybe there's some common electronic parts that I could throw on there, to function like a shield, even if they didn't do anything electrically. Randomly searching Digikey for parts that are tall, thin, and cheap. Some kind of rail or tab or something maybe...