I'm not sure about crafty things for a mechanic dad, but my Pop loves
1) those red rags they sell in auto stores/auto dept.
2) a really good tire gauge (they lose those so often).
3) A device that telescopes (like an antenna) that has a magnet on the end. It is for when they drop something in the engine.
4) Different sized funnels. (they get all happy over those--go figure)
5) huge tub of orange scented oil/grease remover for his hands.
6) curel lotion for after he scrubs the oil off his hands. Heals cuts and stuff.
7) I already bought a model kit with his fav nascar driver. Tony Stewart. Plus glue.
my sister bought my Pop a neat cooler, drink holder for the middle of a bench type seat.
9) I bought a organizer that hangs on the back of the seat. Could make one.
10) a new duffel bag that has his fav team on it, car manufacturer, or tool company.
11) small set of sockets. Metric or American. They lose those all the time, too.
12) mag lite.
13) heavy duty thermos. My Pop throws his in the back of his truck and it can take being run over, etc. (no glass inside). Could engrave something on it. An in-joke for the two of you.
14) of course a new tool box.
15) a more expensive tool box that stays in the garage. They usually come in red and have shallow drawers.
16) another expensive item: new stereo, satellite radio (subscription might be a drag, tho'), new speakers.
17) a really good window cleaner. The type with sponge/netting on one side, squeegee on the other.
18) a couple of really good window scrapers, so he will always have one handy.
19) find out what kind of jack he'd like.
20) an engraving tool, so he can i.d. his tools and stuff.
21) subscription to his fav mag
22) gift certificate to auto catalogs (Whitney's is one)
23) a cool house key that some places sell that have fav teams on.
24) new key fob.
Crafty kind of things.
1) shop shirt with embroidery on it. I'm going to use Sublime Stitching patterns. Like a flaming guitar with his name in it. Every man likes to believe he is rock star. Indulge him. Could do the collar, back or cuffs with a little something, besides the obvious chest area. Could use clip art or copy drawings of cars and use fabric paint if embroidery is too involved. (lots of work)
2) dollar stores have cheap baseball caps and I embroidered a design for my best/f's husband.
3) a cosy for his cell phone
4) I made a grocery bag holder and hotpad with the same fish cloth. Could find car themed fabric.
5) Men love baked goods. Pies, cakes, bread, cookies. Make his own stash. I make my Pop his fav and mail it to him. I like to tell him it is the mail and he's pretty happy for the days it takes to get there, plus the day he gets it he calls and he will tell me "thank you, thank you, thank you!"
6) new key fob. A easy one to make is one or two strips of leather or suede. Put it through a split keyring and thread pony beads and plastic "bone" on and knot it. Use colors he likes or sports team colors.
7) something to hold his car related papers in the glove compartment (registration, insurance info), could be an easy folder type or do a crafster search to find out how to make a pouch with a zipper (zippers--arg!).
a pouch for owner's manual, or a pouch for tools that get lost easy (like L-wrenches or spark plug gap measure-thingies). Use tough material, for the items that will be sitting in a tool box. Could find a sturdy wooden box, decorate it for putting those aforementioned small tools.
9) something you made to hang over the mirror. My Father bought a handmade dream catcher. Could make something that reminds him of you. Small picture decoupaged on a fimo clay item (cube, frame, flat tile), hang it from an elastic loop for easy application.
That's all I can think of, mechanic related.