I created a small cocommand block structure that allows a player to throw a pair of sticks on an armor stand and that armor stand gets arms and subsequently destroys the sticks.

The first command block is a repeat:
/execute @a ~ ~ ~ /execute @e[r=3,type=Armor_Stand] ~ ~ ~ /testfor @e[r=1,type=Item] {Item:{id:"minecraft:stick",Count:2b}}

Then a comparator.

The second command block is impulse:
/execute @a ~ ~ ~ /execute @e[r=3,type=Armor_Stand] ~ ~ ~ /kill @e[r=0.5,type=Item] {Item:{id:minecraft:stick}}

The third is a chain:
/execute @a ~ ~ ~ /execute @e[r=3,type=Armor_Stand] ~ ~ ~ /entitydata @e[r=3,type=Armor_Stand] {ShowArms:1}

Thank you for reading,

A Lymbian

EDIT: It only works for armor stands close-by.

umm i dont get it

when you throw a pair of sticks onto the base of an armor stand, it deletes the sticks and gives it arms.

oh awesome, i wasn't sure i communicated it properly

that makes sense, i didn't think of that, i need to figure out how to fix it.

even then, who would be stingy enough to use only one stick?

i also need to figure out a way to return the sticks.

@JustJams what i mean is that, when you break the armor stand, it should return the sticks

@CraftyMyner how do i remove the comparator because i can't seem to figure out how.

I tried that but it didn't work.