Difficult Retraction Test

If you're printer can pass this you're good to go. You can add scripts to make this a retraction tower. The first layer is 4mm, then each layer after that is 3mm. The height is 16mm

In Cura go to Extensions-->Post Processing-->Modify G-Code-->Add A Script-->ChangeAtZ. Set the Change Height to 4mm. Scroll down to Change Retraction and enter your settings. Do the same for the next layers. Their heights will be 7mm, 10mm, and 13mm.

You can also make this a temperature tower as well. It's a small model and can be printed in 15 minutes or less.