what tools can repair STL model to make it 3d printable

It is an important process to repair STL files before 3d printing.There are several file formats can be used on 3d printer, such as PLY, OBJ, AMF, WRL, and other 3d mesh models. But The most common 3D printer file format is  STL file. Many software packages support this file format; it is widely used for 3D printing, rapid prototyping and computer-aided manufacturing.

3D Printers work with the STL formatted files. Most 3D soft wares, such as SolidWorks, AutoCAD, Creo, can create an native STL file. Some soft wares need to create STL files with an add-on tool.

Even you have many years’ experience in designing and very familiar with the software you use, sometimes you will leave unprintable defects in the model too. So you need software to repair STL files.

Autodesk Meshmixer       Free

It is a free tool for Windows and macOS. You can use this tool to create and repair 3d model easily. And it is an ideal tool for 3d designer to create 3d model based on existing volumes. But if you want to create a more complex model, you need to choose other software. With the tool, you can fix your model, add lattice on your 3d model, resize 3d model, etc.

3D builder                       Free

Microsoft 3D Builder is a free app. You can use it to view, create or personalize your 3d model. You can clean up and automatically repair your 3d model. It has a feature to turn your photos into 3D-it is not perfect, but does work.

MeshLab                        Free

It is an open source tool. There are some tools that can be used to edit, clean, heal, inspect, render, texture meshes. Usually you can use it to prepare models for 3d printing.

Blender                          Free

Blender is an open source and free software. Using the software, you can create 3d models, animation, simulation, rendering, game, etc. And you can edit video, repair STL files too. 

Magics                          Commercial

Materialise Magics is a commercial STL editor. It is an industry-leading data preparation software for 3d printing and additive manufacturing. With this tool, you can repair STL model automatically or manually, prepare build platform, add supports to 3d model, and so on.

Cur3d                           Commercial

After you create 3d models with some CAD software, maybe it is not suitable for 3d printing: overlapping surfaces, too thin walls, wrong normal, holes, etc. Cur3d can fix the errors easily.

Netfabb                        Commercial

It is not only a tool that can be used to repair STL files.

Besides offline tools,you can use some online service to do that.But usually it is only work for simple models.