MobMuPlat (short for Mobile Music Platform) lets you create your own custom audio software for Android via the open-source audio environment PureData.

MobMuPlat hosts a list of user-created documents each of which defines a user interface and audio engine. MobMuPlat can do synthesis sampling networking via local wifi OSC messaging set and query hardware characteristics use device sensors use MIDI and HID devices display images/graphics and much more.
see www.mobmuplat.com for more info.

Creating your own work consists of two parts both done on your laptop/desktop.
First create the audio engine using the graphical programming language Pure Data (PD)
Second either use the native PureData GUI or create a graphical user interface (GUI) with the MobMuPlat Editor.

With PureData and the MobMuPlat Editor open and data sent between the two you can simulate the app behavior on your laptop/desktop. Once development is complete send these files your mobile device and open them within MobMuPlat.

Download these tools from www.mobmuplat.com