It isn't pretty or showy, but it's durable, practically free, and very easy. This is a practical target. I would recommend using up to 55lbs of draw when shooting at this target. I'm not sure how much more it would handle, and it depends on what you fill it with. I used a 40ish lb longbow I made from PVC and it stopped the arrow easily at less than 10 meters. So given different distances and different strengths of bows, durability will vary, but for a cheap target, this isn't half bad.
Step 1: Very Easy
This beautiful target right here is made from a paper bag like you get at supermarkets and filled with more folded paper bags. I reinforced that with cardboard, not really expecting to get anything durable out of it. I was just kind of messing around because I was bored. But as it turns out, it was pretty strong. Like I said in the intro, it stopped an arrow at less than 10 meters shot from a 40+ pound bow.
Put cardboard pieces on the faces, but inside, and really anywhere you want. The more layers the better obviously, but I only used like two or three layers of card board I had laying around.
I taped the top with masking tape and taped around to make it look a little better and to make it a little tighter since the outer bag was loose. Things can be done to make it prettier, but I don't care. I used mason line to make a loop on the top to hang from some hooks down at the range I practice at. It's not necessary, just something for convenience.
The perks are that this target is cheap, easily repaired, easily renewed, and easily replaced. All the cardboard I used I had laying around, waiting to be thrown away. Another good thing is that it's small enough that it's easy enough to handle and promotes good accuracy.
So, just put a paper target over it or shoot as is, and there you go- quick, easy, cheap target that wont fall apart in three seconds. This is also good for beginner archers since every archer knows that it can be an expensive sport or hobby. This is a good way to have something more durable than the one random box you have lying around, and to get a feel for archery. If it turns out it isn't your thing, you haven't lost money on a target at least.
A note about the mason line- it was about five or six bucks at Lowes and is only like the 15lb one. I have seen 25lb, but 15 suits my purposes. It is possible to make your own bowstring out of mason line. I actually did that for my 40+ pound PVC bow and it works just as well as store bought. (for a lot cheaper). Might see another instructable for that, but we'll see.
Have fun shooting everyone