What Am I?: NaPoWriMo 2015, Day 13

You’ll curse as you scrub me off your walls,
but I will keep your secret under wraps
until it’s ready to be revealed. To begin,
you first must find my end. Many things
are better than I for many jobs, and
my maker also makes many other things
for my jobs and the jobs I cannot do.
But when you need me, you need me —
you rummage through many other helpers.
Am I in the gorse and the heather? Call me
with bagpipe and drum. I might come