I can attest to the canned foam gap filler, I have two 3-d buck targets one is 15 years old and the other around 12, the oldest I refill the vitals area every year with the filler and its good as new. The other, well.. I never used it yet! Its sitting in my basement just waiting. Considering the prices of these things i'm trying to get as much use out of the older one as I can. And believe it or not it still looks pretty good.
If anyone decides to use the filler, make sure to use the type that hardens not the one that stays soft and flexible.
Also here are some pictures of my field point target I made this year.
If anyone would like to make one here is what I did..
Its 26"x26''x21" deep. I made it out of 8 milk crates latched together with large plastic ties, then cut out the inner area leaving only a shell, i then reinforced it with some 3/8" plywood and screws. I then drilled a few holes in the top for rope handles. The backing is an old piece of carpet, you might see it on the pics, and i have a 2-1/2" piece of hard foam in front of that. The rest of the inside is old rags, sheets, and clothes. The face is from a screen door I replaced.
Once you fill the shell, stretch the screen and staple it to the inner wood support and paint on some target circles and your done!
The screen material is the type of plastic screening used thats supposed to help prevent rips or your dogs or cats from puncturing it. You can get it at Home Depot in rolls. All in all it was easy to make, is portable and free!(or very cheap if you need to buy screen and a piece of foam)
I looked at targets this past spring and did not want to dump $100.00 or more on one, and considering i made them in the past using a large cardboad box as trhe frame which only lasted one season i felt that making one like this should last many, many years. I'll probably need to replace the screen face in a year or so but so far its holding up well. The kids love it, and I love it, however it just doesn't accept broadheads well.(They go in great but come out pulling out the cut material)