Botch, bungle, fumble, muff, cobble mean to handle or treat awkwardly or unskillfully.
Botch may imply repairing or mending, but it frequently implies a making or forming by patching or by putting together out of pieces.
It consistently suggests incompetence and a spoiling or marring of the thing produced, whatever its character.
Bungle implies ignorance, ineffectualness, or clumsiness in design or execution or an inability to use materials with skill or competence.
Fumble stresses clumsy or unskillful use of the hands especially in uncertain attempts to reach, take, or grasp something or in groping in the dark for something.
Occasionally it suggests the awkward uncertainty not of hands or fingers but of mind or soul.
Muff, a word much used in sports, especially implies an unskillful performance or a bad play (as in catching a ball, firing a shot, or wielding a golf stick).
Consequently muff in more general use often means to fail by bungling or fumbling (muff an opportunity).
Cobble is much like botch, though it basically implies the mending or patching of shoes; in more general use it stresses a patching or putting together of something in a crude or clumsy manner.