Hello all,
just wondering, i’m making a quick model to test the 3d printing of it.
Problem is, 3d printing cost is calculated in cm3, so the model has to be “digged” or you’ll have to sell your car to pay it lol.
Is there a way in Zbrush to make the model “empty” in it ? Like “wall thickness : 2mm” for example ?
Finally found a way that should work : create shell in the dynamesh section.
Problem is : each time i try to create a shell of the model, it keeps telling me that it requires a sub-mesh insert 
What i do is inserting one or two “insertCylinder” brush in my model, unmask all, and click on “create shell”, don’t know what i’m doing wrong :s
Make sure your mesh is a dynamesh. Then use mesh insert cube/cylinder and insert it in the bottom of the model (hitting Alt while you do so makes it a subtract object . This subtract must leave a hole in the bottom (but you want this anyway, otherwise the material the thing is printed from has no way of draining). Activate create shell, and mess with the thickness (this is trial and error as far as I can see). Once you control click twice your mesh should have a hole in the bottom and be a shell.
Pressing Alt while inserting the mesh was the solution, thanks a lot !