Gluing four regular hexagons to form the surface of a regular octahedron. Example given (with a different net) by Elena Khramtcova and Stefan Langerman, "Which convex polyhedra can be made by gluing regular hexagons?", <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180920234826/http://www.jcdcgg.u-tokai.ac.jp/JCDCG3_2017_abstracts.pdf">Abstracts of the 20th Japan Conference on Discrete and Computational Geometry, Graphs, and Games</a> (2017), pp. 63–64.
<a href="//commons.wikimedia.org/wiki/User:David_Eppstein" class="mw-redirect" title="User:David Eppstein">David Eppstein</a>
<span class="int-own-work" lang="en">Own work</span>, based on <a href="//commons.wikimedia.org/wiki/File:Euclid_Octahedron_3.svg" title="File:Euclid Octahedron 3.svg">File:Euclid Octahedron 3.svg</a>