Healing Non-Manifold Objects with Blender

Have a marginal STL you found on a community sharing site that doesn't slice well? This video shows a simple way to heal that STL and make it printable. After making this I learned that you can click (deselect) the camera icon in the boolean operation to avoid the "double whammy" of calculating the operation twice.

Update. See comment below. There is a 3D Printing toolbox add-on for Blender that makes this a little bit easier. It's not 100% reliable, though. You can always fall back to this method, which has proven very reliable.

[GridSpace]

This will work for many objects and not for others. There are infinitely many ways meshes can be broken and non-manifold. If this isn't working for you, then your mesh likely requires a human to inspect and repair the defects.

[GaWoP]

I am using Blender Version 4.1.0 (4.1.0 2024-03-26) and unfortunately did not have the same luck with this particular approach. The "Self" intersect method is not longer an option. I attempted a similar workaround where I applied the modifier to the cube and used "intersect", and it appeared in the viewfinder to have similar results, but it didn't fix my manifold issues. I am saying this in hopes that this alternate approach works for others and that it was just a personal issue with my particular geometry.

Another approach that did work for my geometry was the "Remesh" modifier. I used the "Voxel" approach in the remesh function with a sufficiently small mesh to grab all the fine curvature of my model. This worked, but warning that it was very memory intensive. It took me a couple iterations to find a sufficiently small resolution size such that it (1) captured all of the curves in my model and (2) didn't crash my application because of how small I was refining.

Good luck out there!

[gunsboy]

Man, I watched dozens of videos using face orientation, solidify, shrink-wrap modifier, and a few other ways. This is the only one that worked.

[hoenigmarkus]

You can avoid the double load time by deselecting the "Realtime" view. It is one of the 3 small buttons on the right side of the word "Boolean". If you have the "Realtime view" deselected it only loads once, when you press "Apply"

[roberte]

Perfect solution! Allowed me to print two minfigs that I've spent hours trying to fix. As always the simplest solution is the bet one - Many thanks!!!

[jackkuehneman]

3 years later this video still helpin folks. thankyou sir!

[sadwahwah]

Holy moly you're a genius, I've had so many problems making meshes in blender never once did I think of this

[Boneappleteahee]

I kid you not I was converting a Game model into a printable 3D model and only 1, face was broken. I retried converting it many times. You just saved my computer from its first flight.

[gregdavidd]

I always just open the object with Microsoft 3D builder, Import and Fix. Works every time. So quick and easy. Often Im sloppy with my own files and that fixes them too. I export my model from Blender to STL. I open the STL in 3D Builder, import, fix, save. works in Cura every time.

[connorquinn]

Literally a life saver! Been trying to 3d print some game models that were definitely not meant to be manifold and Cura was going nuclear lol

[gitbse]

I've been struggling with this exact problem for so long when modeling in Blender. I'm not kidding .... this is (jokingly) life saving.

[GoatPrint]

Thank you for this tutorial!!! I've been 3d scanning trim pieces in my truck and the output is always non manifold big pile of vertices. I had to ensure I solidifies the faces first and also made sure that materials in the modifier is set to transfer from the cube. 🎉

[alfredoguzman]

thanks man that was so clear, easy and informative ive been watching videos learning BLENDER and so far you are the best.

[baldeagle]

This is the very stl I was trying to fix. I'm making my daughter a Hobbit bookcase diorama for Christmas. You've earned another subscriber, thanks.

[miketully]

LOL! "Borg Cube this"
Seriously I really appreciate this fix. I don't 3D print, but I make a habit of being absolutely certain that ALL my objects are completely free of any Non-Manifold issues before and after doing a Boolean operation. I often work with truly HUGE models (like a ship over a mile long), and with having people walking around in it I've found that pretty much any Non-Manifold issues, although not visible in long shots like (exterior establishing shots) renders look fine, but in comparatively close in shots (like two people walking through where a 50 foot diameter transfer tunnel intersects with a complex object that forms a part of the ship that's more than 1800 feet across) tiny Non-Manifold issues will cause artifacts twice the size of a man and be VERY apparent. Prior to finding your solution this could be a horrendously time consuming problem to fix.
Thank you for posting this!

[blunaa]

In blenderwith your object selected hit: Tab, A, M, by Distance.
Most slicers I believe also have options to repair non manifold edges

[TerranceLam]

THANK YOU! I have been importing my files into freeCAD or other programs and sometimes it worked and sometimes it didn't. This is way better and works with my own blender-created files that I create and clean up for later distribution. Much appreciate this video.

[setver]

Man I feel like i owe you more than just a like and sub. This is the best quick fix I've seen to date. Thank you!

[mmdip]

Wow!! I’ve been looking for this for ages. Thank you 🙏🏻

[diva]

"What the flapjacks!" lol Great tutorial! Thank you very much!