I wanted to test cooling fan performance objectively back to back, so I designed this part to help.

Previously I had noticed the AIO micro 3D printer test did a good job of showing up the flaws of a lack of cooling fan, so I modelled a similar design. The main body is lifted up off the bed to allow a wide and difficult bridge. There are four gradually tilted arcs, from vertical to 80 degrees, pointing up, down, left and right. The reason to see if a fan that only blows from one side is at a disadvantage. The final feature is a central spire that is raised above the rest.

Version 2b was my final design, I recommend only printing this one. The others are included for completeness.

This process is covered in detail in this video: https://youtu.be/xmZCwJDyxYU