This is made to fit snug around the Seagate STGX1000400 (1TB external HDD from Amazon).
It is generally advised to also use a Y-splitter in order to be able to deliver enough power from the rear of the wiiU itself.
This print does not require any supports if printed up-right, but I highly recommend adding a brim (I did an inner/outer one of 10mm) like the following;

The stand is optional in case you want to put it upright - you will need to print the “wiiU-HDDstand” twice.
The author marked this model as their own original creation.