I bought ArtRage for Android months ago and I've been doing a few 600x600 doodles with my finger on my Samsung Galaxy S5 using it. Most get posted to Instagram too. Here are 5 more of them.
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Summer Alexander:

"Another drawing with my finger on my S5. My Alexander character
Accidentally erased the wrong line and left another so he looks like he has 6 fingers."
( Fullsize )
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My #AVEX2015 Tuesday outfit:

"S5 doodle of me and the outfit I wore on Tuesday. Hiram McDaniels shirt, camouflage tights, & pink hair band with pink lipstick."
( Fullsize )
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Zinnian:

"Another S5 finger doodle of my Zinnian character. I kinda gave-up when the Watercolour ArtRage for Android brush wasn't doing what I wanted."
( Fullsize )
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Theodore:

"Finger doodle of the sinful dork. Probably thinking about escalators or such!"
( Fullsize )
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Female Protagonist:

( Fullsize )
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Summer Alexander:

"Another drawing with my finger on my S5. My Alexander character
Accidentally erased the wrong line and left another so he looks like he has 6 fingers."
( Fullsize )
---
My #AVEX2015 Tuesday outfit:

"S5 doodle of me and the outfit I wore on Tuesday. Hiram McDaniels shirt, camouflage tights, & pink hair band with pink lipstick."
( Fullsize )
---
Zinnian:

"Another S5 finger doodle of my Zinnian character. I kinda gave-up when the Watercolour ArtRage for Android brush wasn't doing what I wanted."
( Fullsize )
---
Theodore:

"Finger doodle of the sinful dork. Probably thinking about escalators or such!"
( Fullsize )
---
Female Protagonist:

( Fullsize )