Pretty nice grinding job for a 9 yr. old
FYI- if you're changing cable sleeves and need a new end, the Help section(Dorman products) at most auto parts sells a variety pack of screw held brass barrels(throttle cable parts)- if the removability isn't an issue then you can solder it with a propane torch or soldering gun- if leaving the house to find a bike shop isn't feasible like late evenings!!. Also filing/grinding down a factory lead barrel is pretty easy if the cable has the wrong size end.