Originally Posted by
fietsbob
Fold the tools you need in a piece of canvas, roll it up and tie it under your saddle,
with a toe strap..
if you fold it all up in or with a shop towel
you will have something to wipe off your hands upon.
+1 ...and here are more instructions.
http://www.rivbike.com/product-p/ba-rito.htm
You could make a dandy one if you cut up an old pair of jeans.