I'm trying to fill this license plate indent on my bumper. Im thinking about cutting a piece of plastic and epoxy it to fill the hole but what filler should I use to fill the whole section? I know regular body filler will not stick to plastic. Is this a good idea?

Get a donor piece of bumper from a salvage yard with a flat enough surface to harvest a good "slug" piece to fit into the spot you want to fill. Make a template out of card stock or cardboard, first. Here's the 3M product I use:

http://3mcollision.com/3m-automix-ez-sa ... 05895.html

You will need to sand the surfaces to be mated (sand the edges so there is a "V" shape where they meet). This will also require adhesion promoter before using the epoxy.

No need for any glazes, fillers, etc. -- just use the 3M epoxy and it will sand out and feather nicely. Before doing the outside you should put backing pieces in place and use the same epoxy to reinforce/glue them behind the seams.

Note that if your bumper is SMC or Fiberglas (which is unlikely unless an aftermarket body kit), you cannot use this particular 3M product.

BTW, your photo doesn't show up here it looks like you are trying to link from some other forum...that doesn't work since the sending site does not allow it.