Hi!

I am new to 3d printing and 3d modelling, and I need some help.

I am looking to make some biscuits for my son´s birthday, and I want to make a negative mold from this figure http://www.thingiverse.com/thing:200099 I posted on thingiverse.

So, here is the question, after you have a STL model, how do I make a negative mold from it? On OpenSCAD make a cube and then subtrack? How? (I am new to Openscad as well). Or maybe on netfabb basic or meshmixer.

Thank you for any help