On: Monster Mash: A Sketch-Based Tool for Casual 3D Mo...

[samstave]

ZbrushCoreMini is free, and may do what you are talking about:

http://pixologic.com/zclassroom/workshop/snapshot3d

https://zbrushcore.com/features.php

[hypertele-Xii → samstave]

I don't see a "mini" anywhere, all listed products have a price.

[samstave → hypertele-Xii]

Create account, flood leads to DL, create an account and it will inform you that “because it is free you wil not be died for a license.

Just DL and instal it and you are all good.

But you do need to make an account in Paul Graham’s name to confirm you like the software.