Here is CAD Challenge #25 from the CAD subreddit. This time I will create a octahedron using only two sketches and two extrudes. In the links below I included both the solution and the alternative method shown in the beginning of the video.

link to the challenge: https://www.reddit.com/r/cad/comments/6c1wgd/cad_challenge_25/

Solution in Solvespace: https://my.hidrive.com/lnk/Y66HBNcu7

For those interested, Raul Randall made a video of his solution with FreeCAD here: https://www.youtube.com/watch?v=RXaTkLbKs3U&t=208s

For this video I used Solvespace 2.3 on OSX.

Solvespace is open source (GPLv3 license) and is available for Window, OSX and Linux. It is developed by Jonathan Westhues and maintained by Whitequark and others. It can be downloaded here: http://solvespace.com/download.pl