Sometimes I need to trim down the bits and pieces I use in the keys. Most of the time I use wire cutters to nip off the unwanted parts. This generally results in the excess metal pinging off somewhere and eventually (hopefully) being swept up on those infrequent occasions that I clean my studio.
Most of the time I use Golden's heavy duty gel medium to hold all the bits and pieces together. I am very grateful to a very generous and encouraging craft artist who suggested this product to me years ago when I was first venturing into the world of mixed media.
I like this stuff: it's non-toxic, practically odourless, somewhat flexible, and cleans up easily with water. And it's easy to remove and start over if something is not working or crooked.
Sometimes I use E6000 if the join between two pieces is very small. E6000 is smelly, toxic, and possibly cancerous so I avoid it whenever possible (but not all the time, because if I need a strong glue I need a strong glue and isn't death inevitable anyway?).
I use a paint brush to apply the gel and add extra gel medium when holding the end bits on:
I usually prop up the bits on top of other bits until they dry (either overnight or during the work day).
The round white disc is holding up the glued on silver bit.
The gel dries clear (except when it's on something copper - then it reacts and creates a lovely green patina).