When you have a project on display and need to keep little fingers out, an acrylic shield is useful. This project uses 3D printed brackets to mount the shield to a plywood base.

Parts:
Acrylic I used 1/4 inch thick, 2 sheets 18 inches by 48 inches and 2 sheets 18 inches by 36 inches estreetplastics.com
6/32 by 1 inch machine screws
3D printed brackets--design and print files here:
http://www.thingiverse.com/thing:102023

Building this in a "U" shape is critical for strength. The brackets hold everything together and secure the acrylic to the plywood base.

Step 1:

Mount the base pieces to the plywood and insert the acrylic into the slots. Do not push or lean on the acrylic at this point or you risk splitting the bracket or the acrylic.

Step 2:

Gently push the corner piece over the top corner (there is a left piece and a right piece). When the acrylic is snug and "square," drill holes through the acrylic (to match the holes in the bracket) and fasten with the machine screws.

Step 3:

Add a bracket in the center (top) for extra stability.

You can't swing on this like a gorilla or something will probably snap; but this arrangement survived two days at the San Mateo Maker Faire, so it is workable.