tin·ker 
(tĭngkər)
(tĭngkər)n.
1. A traveling mender of metal household utensils.
2. Chiefly British A member of any of various traditionally itinerant groups of people living especially in Scotland and Ireland; a traveler.
3. One who enjoys experimenting with and repairing machine parts.
4. A clumsy repairer or worker; a meddler.
v. tin·kered, tin·ker·ing, tin·kers
v.intr.
1. To work as a tinker.
2. To make unskilled or experimental efforts at repair; fiddle: tinkered with the engine, hoping to discover the trouble; tinkering with the economy by trying various fiscal policies.
v.tr.
1. To mend as a tinker.
2. To manipulate unskillfully or experimentally.
[Middle English tinkere.]
tinker·er n.