A 3D-printer torture test. Highlights cooling, overhangs, stringing, bed adhesion and more.
Please note that this is not an easy print, ensure proper bed adhesion before attempting this.
I wanted a model to use while finding the optimal layer height for overhangs and to verify that my custom cooler has effective and even cooling over 360°

Print recommendations
Maximum cooling!
For me, best results on overhangs is around 0,12 to 0,16mm layer height.
I used two walls, no infill.
Use a brim if you don't have great bed adhesion. I printed without a brim on a clean buildtak without issues

Understand and improve the results:
-Use maximum cooling, if some legs looks bad and some good, your cooler may not be cooling evenly. But it can also be settings related, if the printer is printing one leg last on a layer and then immediately continues printing the next layer on the same leg, it will get hotter than the other legs. Try playing with the Z-seam settings or rotate the model to see if the issue moves to another leg.
-Look for how well the overhangs looks on the legs, experiment with slower speeds and lower layer heights to improve. But don't go lower than necessary, in my experience a too low layer height causes more upwards curling on difficult overhangs.
-To find the best retraction settings, start at 0mm and increase retraction length by a small amount until the stringing stops improving. Try to find the shortest retraction that gives the best result. Next try different retraction speeds, faster is desirable but not always better. Try adding a small amount of coasting to get rid of the last fine strings. Too much will lead to under extrusion though! 
-I generally recommend against lowering temp but it is something you can try.

Try not to change more than one thing at a time.