Been there seen it tried everything and this is the bitter truth. For field point use get yourself as big a card board box as you can find stuff it full of rags and your GTG shooting FP for good. When you start to shoot out the front of the box just tape a new piece of cardboard over it and your back in business. I found and use a 3' square box that works perfectly.
Fixed blade BH's are a different story. Your truly good options DIY are rather limited. if you live near a factory that makes foam padding you can go to them like I did and obtain a roll of foam padding large enough to make a 4' long 3' high and 3' deep target.
Much to my complete disappointment that factory has since changed plant managers and they will no longer sell small amounts of foam padding to private individuals like myself.
There are a multitude of places on line you can either buy sheets of foam padding to make your own DIY target or make layered or solid foam targets suitable for BH use but most are not very affordable and the ones that are aren't very durable.
If you can find a carpet store willing to let you have the foam padding it has thrown out it could work well but beware it will likely be full of hundreds of staples that can play havoc with carbon arrows and FB/BH's. Also if you can find a carpet store willing to let you have a several hundred 2'x2' squares of commercial carpet that is meant to be removed and replaced it has in their dumpster it also could be used to make a killer FP target, but i don't think it would work to well with FB/BH's.
The places that sell expanding foam that works well for shooting fixed blade BH's into is VERY expensive (I've checked MANY and your're talking $200-$300++ to make one not very large target) to the point it's actually IMHO and budget quite cost prohibitive considering how quickly they wear out and if ANYONE reading this has found a source for affordable expanding foam suitable for FB/BH target construction please share it with the rest of us.
The best option I have found for a foam target suitable for shooting FB/BH's into are called Blob targets, but the larger ones (3'x3' or larger) are so God awful heavy (200lbs+) their shipping cost is a deal breaker and for me, but they do sell smaller targets that can be shipped.
If you try to use sheets of building insulation it will end up making a considerable mess in your yard, it aint cheep and will wear out VERY quickly, and cans of spray foam like "Great Stuff" just doesn't work well enough again IMHO. But I have been kicking around the thought of mixing in shredded paper with great stuff to try to give it enough durability to work but haven't tried it yet. Basically all the alternatives to foam suitable for FB/BH's from staked card board, foam insulation, or expanding insulating foam simply don't work all that well and begin to fail after a very low number of shots.
One alternative I have heard people try that has worked decently is large amounts of scrap plastic wrap and or bubble wrap used in packaging large items for shipping. If you can get your hands on a very large quantity sufficient enough of either for free from a business's waste and compress it between sheets of plywood with enough force you could make a workable FB/BH target.
But besides the layered foam targets available on line or Blob Targets your options for affordable suitable FB/BH targets is quite limited and bottom line is even the best (which are also again IMHO VERY expensive) OTC commercially manufactured FB/BH targets simply aren't going to stand up to hard use and extensive hits from FB/BH's, and for me in my opinion when I factor in cost VS how long they last they ( best made OTC foam FB/BH targets) are simply not worth their considerable cost.
If anyone knows of a source of foam durable enough to make a killer FB/BH foam target from that will last for at least two possibly three seasons of use that is also affordable enough to make a 3'x3' target that costs under $150 please by all means share it.
For a cheap easy transported virtually indestructible FP archery target IMHO a huge box stuffed tightly full of rags is simply unbeatable. I have two 3'x3' heavy duty cardboard boxes that have taken 1000's of FP tipped arrows and all I do is replace the worn out card board and I'm back shooting in minuets.
