This thing was made with Tinkercad, but you can design your own in the Customizer: http://www.thingiverse.com/thing:93859



We use wedges like these to block open doors like a doorstop or at the hinge. Two wedges can be pushed together inside the frame of a sprinkler head to shut off the (copious) flow of water. Not sure if ABS is up to the stresses of closing a sprinkler head - I guess I will have to test. Print it in a bright color so that you don't lose it on the fireground.

ATTENTION
This work is licensed under the Creative Commons - Attribution - Non-Commercial license. This license applies only to the files and documents available for download from the Thing Files section of this Thing.
All other related content (photographs, videos, and verbiage such as contained in "Description" or "Instructions" ) are excluded from this license. with all rights reserved, unless specifically available for download This notice constitutes a clarification, not a change, to licensing for this design.

The observant reader will notice that I didn't print this in a bright color...

Also, the narrow tip of this object curled upwards a bit, maybe from when I pried it off the Kapton, but it may have been curled before. I made another version with less of a point and it curled less. I have much to learn, but this came out well.
I find watching the lattice of interior fill get printed fascinating. Stay safe!