*why does it have those bumps on the handle?
Easier grip with either a single fingertip or two of them, allowing for easier control of tension, or holding it in the keyway.
*why isn't it bent 90 degree?
It didn't want to when I heated it.
Later discovered that the design actually worked better than if I had put a full bend in. Limitations of the material (hacksaw blades) is another factor...even red hot, that stuff remains somewhat brittle. Radius instead of angle bend means more strength.
*what type of locks do you use it on?
Whatever locks using it on would make picking more convenient. I've found it to be effective for using perpendicular to the keyway. Worked pretty well for a keyed combination lock - really small plug in them.
*what material is it made of?
Standard carbon steel hacksaw blade, heat treated to add a little more resiliency.
*how would you actually hold it to apply tension with it?
Depends on the lock and the keyway, mostly - as it does with any improvised tool. Either a fingertip in one of the valleys or holding the end by the valleys to keep it in the lock/apply tension simultaneously.
*what are the strenghts/weaknesses of this design?
Adaptability and convenience in a potentially large number of locks it can be used on/awkwardness in tension control due to tip angle and bend radius. As stated before, it's designed to be used in a situation where it'd work slightly better than your typical wrench would...or to work on the most possible locks.
I'd imagine that you'd have slightly more dynamic plug control with it in some situations.
*why does it have 3 bumps instead of 2? (I'd think one on each side of the finger that pushes it)
Symmetry and fatigue control - hole on the end is from a hacksaw blade. Two valleys for fingertips also allow more options to the end-user. May as well put them there, better to have them than not.
*anything else you think anyone should know about this design.
Well, it's certainly not the best, but in practice I'm finding it's not the worst, either. Adapted and refined it from a similar wrench I saw made by someone with a good bit more experience at picking. The valleys in practice are a little bit thicker - around 3/32" instead of the designed 1/8" - but most people aren't going to be able to work to that precision.
*I really like the shape of the tip, but I the handle is too much slimmed down for my taste.
Bear in mind it was made from a now-defunct lockpick attempt, so by necessity it had to be a little on the small end of the scale. Good for sticking unobtrusively on a keychain.
For awkward keyway positions where it wants to jump/twist out, added size would be a detriment because of leverage.
Gracias for the praise.
but for real, those bleaprints are 
