Android STL File Viewer (Free)
Download and install the app from the Android Market. When you run the app you are presented with an opening screen. The banner at the top takes you to the web site of the app's sponsor, Solid Technologies. The next choice (the ball icon) opens the file browser which shows just folders and STL files. Select "View STL files". The first time you run the app you will see the contents of the top level storage folder in your phone. Scroll down and click on the folder /sdcard. Now scroll down again and click on /sdcard/download where you will find any files downloaded from the web. Alternatively, if you have put STL files elsewhere on your phone, navigate to them by clicking on folders. The top item in every list is "." which reloads the current folder, and the second item is ".." which takes you up to the parent folder.
The app remembers the last folder viewed and returns there automatically on startup.
When you see a file called (for example) enneper.stl, click on it and the STL file will be displayed. Click and drag on the screen to rotate the model in any direction, use two fingers to pinch zoom in and out or use two fingers to drag.
If you are using a phone, you may be holding it in 'portrait' mode (the screen is taller than it is wide). Try rotating it and the display will reformat to follow you. Some larger 'tablets' default to 'landscape' format (wider than they are tall), but either way is good. The display reacts according to how the device is shaped and how it is held.
When using the file browser, there are just two menu options, Settings and About. When you are viewing a model the menu includes further options:
Settings: Allows you to toggle on and off various elements of the display:
- Show facets: the STL model itself (sometimes referred to as a mesh) which is made up of a collection of triangular facets
- Show vertices: each triangular facet, as you might expect, has three corners, these are called vertices and they are shared by adjoining facets. They can be highlighted by clicking this check box
- Show XYZ axes: displays the X, Y and Z axes (red, green and blue)
- Show bounding box: the smallest xyz aligned rectalinear box which encloses the model.
- STL Model Colour: Change model colour (R, G, B or grey)
Stats: Facts and figures about the current file: the name, size and load-time, whether it is a binary or ascii file, the number of facets and the dimensions, including STL model volume.
3D Quote: Emails a copy of the current STL file to Solid Technologies in Pennsylvania, USA for a quotation on a 3D print in a range of materials.
Reset: Spins the model back to its starting position, size and rotation.
Screenshot: Takes a screenshot of the current model, exactly as it appears on the screen, and saves it as a PNG file on your SD card. The file name is STL.your_file_name.PNG. The file is saved in the root (top-level) folder on the card.
Invert: If your STL model looks odd (perhaps too dark, or you seem to be seeing part of the inside of the model and not the outside) some or all of the facets may be inverted - facing the wrong way. You can't fix that with this app, you need to go back to the software you used to create the file and reorient the facets. However, this menu option just flips all facets so they face the other way. If that makes your model look right (though darker than a correctly formed model) then you definitely have incorrect normals.
About: Some brief details about the app and links to this site.
Sample STL Files
Want to try out the app out on some STL files but don't have your own ready yet? Try these:
An ASCII STL file of a tetrahedron; 4 facets. As simple as it gets.
A 'catalan' isosurface; 36,860 facets. Just a strange shaped surface, created with K3DSurf and Rhino3D.
A wire frame dodecahedron; 68,832 facets. One of the Platonic solids, built by a script running in Rhino3D.
Another isosurface; 223,104 facets; 12 facets. Again from K23DSurf and Rhino3D.
Go Pro! (it's FREE!)
The Pro version of this app adds the ability to view point cloud files from 3D scanners. Medical, dental, architectural, engineering, geo-survey - all kinds of 3D scanning and measuring systems generate point cloud files. The Pro version automatically detects many data formats and displays them in the same way as this app displays just STL files.