Need advice with combining parts:
I generated a buste out of #LEGO bricks with #Brickr. Now the model consists of many parts. How can I combine all parts into one? Is there a programm which does this?
Try Meshmixer (Function “Combine”).
Well, if it’s truly made up to lego bricks, that means that there’s a lot of empty space inside. You’ve got separate pieces with some coincident faces, but each piece is mostly hollow. There are plenty of programs that can do boolean unions to combine pieces that are overlapping, but they’re not designed to merge pieces that are only touching. What you need is a non-convex hull operation, but there’s not a single solution to that function. Some programs have a “shrinkwrap” function that may or may not work, since each piece is separate.
If you could do a convex hull of each individual brick, you’d lose the shape of the bumps on top of the bricks, but that would create the overlap you need for a boolean union to work. Short of that, unless the program you used to make the model has an option to turn what you’ve built into a solid shape, there may not be any software that is capable of doing what you want.
Of course, this is assuming that each brick is modeled as a manifold shape matching real lego bricks. If the programmers cut corners and either gave the pieces flat, closed bottoms, a simple boolean should work. If they left the meshes open on the bottom rather than modeling the inner (hollow) space, a basic mesh repair should close the bottom of each with a flat plane, which would get you to the same place.
Try https://brickify.it ?
Zbrush would be great for this. It can shrink-wrap the outside surfaces, removing any internal geometry. There are several options, I think zRemesher would work best for this application. A high resolution (800 or so) with a weak smoothing modifier (4), followed by a mesh projection onto the original, then finish up by decimating the mesh to about 20,000 poly before export to stl.
@Nathan_Walkner Here you go: Geometric Computing Laboratory ‐ EPFL
@Chris_Burger Sounds good but also difficult. And ZBrush is not free. So too expensive for just a fun project.
@enhydra I’d be happy to do it for free, or try anyway. Would be a few hours before I can try
@Chris_Burger Sounds even better. 
Will send you the files tomorrow. I have to go to sleep!
Sounds good
@Chris_Burger Here are the files (original scan and voxelized version): http://we.tl/09ESFYwYoG
If it’s the case that you only want a voxel appearance (not specifically Lego, just cubes), then Blender’s remesh modifier will do the trick from beginning to end (it gives you only the outside mesh, not a bunch of cubes stacked with interior stuff needing to be removed). I took your original and applied the modifier:
https://app.box.com/s/l9omyyyod8df9s2ame36qerpffzc0z1e
(The bottom of your obj leaves a bit of overhang, BTW)
@enhydra I was very busy last night, and today is my bday, may not get around to it tonight, but I will try.
@Chris_Burger Slow down, I’m not in a hurry. Congratz to your bday, enjoy the day and let the others work for you (sorry, I’m Swiss and English is not my mother tongue).
@kongorilla Cool, thank you very much! Indeed, I’m actually looking for a voxelized version. Will take a look at it tomorrow.
@enhydra I enjoy helping people, and not everyone has the same access to tools that I have, so I don’t mind one bit!
I saw your other comment that you really just want a voxelized version of this model, not necessarily a Lego brick version. If that’s the case, the Zbrush remesh tool does exactly that. Did you want the voxelized resolution similar to the Lego brick size, or was that an arbitrary size based on tool availability at the time?
There is a freeform warping function in fusion 360, may this lead to your result?
@Chris_Burger The size of the voxelized version does not matter. 
I set the resolution in Brickr to 50 but I don’t know exactly what it defines. 