37-Spike Caltrop

This CAD model was designed by Oskar van Deventer, copyright (c), 26 September 2025.

37-Spike Caltrop is caltrop with, well, 37 spikes. Regular caltrops have four spikes in a tetrahedral configuration. This object always falls such that one spike is straight up, ready to puncture tires. One can easily design a six-spike caltrop based on the geometry of a pentagonal pyramid. It has the same property that there will always be one spike straight up, when it rests on a flat surface. Also 37-Spike Caltrop has this same property. There will always be a spike straight up. Conversely, one can point each of the spikes straight up, and the object can rest on a flat surface. There is a straightforward approach to make a Caltrop with almost any number N, if either N-1 is odd, or N-1 is dividable by an odd number. This leaves out all N-1 that are a power of two. Hence, an open question is whether there exists caltrop with 5, 9, 17, 33 or 65 spikes.

Here are some links about this design.
https://www.youtube.com/watch?v=Z68mWS1qoSs

Feel free to 3D-print an extra sample to give to a friend, as long as you mention the designer and don't charge money.

If you are planning to sell some samples, then please contact me for a license agreement. The royalty fee is 10% of your selling price.

Please do not upload the design to a commercial service, or redistribute the design in any way other than linking to the YouTube video: https://www.youtube.com/watch?v=Z68mWS1qoSs

Enjoy!

Oskar
11 October 2025

Contact: 
https://oskarvandeventer.nl/index_contact.php?subject=Print%20It%20Yourself