Ringdroid

Ringdroid is free app creates ringtones, alarms, and notifications from MP3, FLAC, OGG, WAV,AAC(M4A)/MP4, 3GPP/AMR, MIDI files. Cut the best part of your audio song and save it as your Ringtone/Alarm/Music File/Notification Tone.
Make your own unique free ringtones is fast and easy. You can set the starting and ending notes by sliding arrows along the timeline, by pressing Start and End to record the point, or by typing in time stamps. This app is also a music editor/alarm tone maker/ ringtone cutter and notification tone creator.
You can also record your own or your kids’ voice, and make them to ringtone or notification. Enjoy reminding you to answer the call with your child's voice.

Features:
Copy, cut and paste. (So you can merge different music files together very easily.)
Fade in/out for mp3.
Adjust volume for mp3.
Preview the Ringtone files and assign to contact.
View a scrollable waveform representation of the audio file at 6 zoom levels.
Set starting and ending points for a clip within the audio file, using an optional touch interface.
Play the selected portion of the audio, including an indicator cursor and auto scrolling of the waveform.
Play anywhere else by tapping the screen.
Save the clipped audio as a new audio file and mark it as Music, Ringtone, Alarm, or Notification.
Record a new audio clip to edit.
Delete audio (with confirmation alert).
Assign a Ringtone directly to a contact, you can also re-assign or delete the Ringtone from contact.
Sort by Tracks, Albums, Artists.
Manage contact Ringtone.

Default save path, you can change then in setting of "Ringdroid":
Ringtone: Internal storage/ringtones
Notification: Internal storage/notifications
Alarm: Internal storage/alarms
Music: Internal storage/music
Music not show:
Android system is very slow to update its music database, so it takes time if you just download your music. You can use "Scan" menu of "Ringdroid" to force update.
Google Play Music can't be display, as it's hidden in special way, other app can't access it.
Workaround : You can access Google Music with the Chrome browser on your phone. Select the desktop site. Select your desired song, click on the 3 dots on the right. A window will pop up, giving you options, including download to device. Download and then use “Ringdroid”. It will now be able to be found on your device.