Here are a few options for Android devices.

Theappalso lets you add things to your collection and send them to theMakerBot appfor instant printing.

eDrawings

The eDrawings app is a mobile 3D image viewer with some unique features.

Thingiverse Android app

Makerbot

Makerbot offers an iOS app specifically for its 3D printer.

Desktop and Web-based Apps

There are few free desktop-based apps for 3D printing.

There are also several good apps that are web-based for those who prefer a larger screen when designing.

Autodesk Meshmixer with a 3D bunny

Tinkercad

Tinkercadis an online 3D design modeling app.

Some other features includePNGexporting and sending the 3D design toAutodesk Fusion 360and 3D communities.

Upload your image in black and then set the thickness in gray on their website.

Tinkercad open with a 3D ring

SketchUp

Another web-based drawing app isSketchUp.

This 3D printer app isalso available for download.

Shapeways with 3D material options