# 3D Design / 3D Scanning / 3D Modeling > 3D Modeling, Design, Scanners >  Negative Mold from a STL Model

## ojaneri

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

----------


## ojaneri

I am trying to do this on OpenScad



difference() {
	translate([0,0,0]) cube([100,100,20], center = true);
import("mario.stl");
}

it renders the cube, but not with the mold. If I just use import("mario.stl"); it opens okay (the.scad file and the .stl are on the same directory).

Anyone can help?!

----------


## schneck007

you can try blender. make cube large and wight like the modell. cover the modell in it  and make a boolean differenz.

if you need help just pm

----------


## WildZBill

I tried something similar which did not work. Perhaps if you tried it with half the cube, twice? Once on each side?
I will experiment and get back to you if I have success.

----------


## 3dkarma

This is old, but worth a reply anyway.  The reason the openscad difference didn't work is because of errors in the original STL file.

----------


## RobH2

Just a thought. Are you trying to make a negative mold that you'd now use to prepare food in. You can't use ABS for that as it's not safe for food. PLA is if you get "foodsafe" PLA. 

You could print the shape as it is and use it to make a silicone mold that you could cook in. Make 5 or 6 of the shapes, pour a tray of foodsafe silicone, press the part in to the 1/2 way point and wait. Then pull the parts out and you have a washable and reusable silicone cooking appliance.

----------

