For loading 12 ga "Poppers" could oneONLY use 20-25 gr of powderand a stiff cork/felt spacer to hold the powder in place nothing else. No wad/no filler/ no crimp. Would this work?

I used to load "blanks" with my old MEC 250 years ago. If I remember right, I used the standard powder charge for whatever I was reloading at the time, filled the rest of the casing with fiber wads, which was before the plastic wad/shotcups came out, and crimped them to hold the wads in place. I sent my father out squirrel hunting with them one time, and he came back to camp so disgusted and mad that it was years before I told him what I had done. They worked really well. I am not sure if you can even get the old fiber wads anymore, as I've not loaded any of them since. You might check with your local gunshop/reloading store and find out if they can still get them for you. One word of advice: Don't shoot them at anyone at any close range, as the wads will still penetrate for a distance. They are, after all, solid material being fired from a shotgun, and can still cause harm.

Would it work to use onlyONE spacer and no crimp??????? Would it have
enough pressure to blow the spacer out of the barrel?????

I would imagine that it would, but you probably need to add enough resistance with some wadding to build a little pressure in order to get much of a "bang". You want to simulate some shot weight in the shell.

something my father inlaw would do is load up a field load just as you would normally but instead of adding shot he would melt wax and put it in place of the shot pellet he'd let the wax cool a bit but while the wax was still soft he would then crimp the shell. he would make these to pop off on the 4th of july. they are just as loud as a regular load. I'm not sure how dangerous these could be, he never had a problem with them but just incase I would step back pretty far just to be on the safe side. naturally I dont recommend anything thats not printed in a reloading manual so if you choose to do this its entirely at your own risk. I suppose have fun, and I wish you all the luck in the world that you dont blow yourself up.

Thanks for the info. I email a couple of suppliers for recipes, but no response. Some has suggseted using rice to fill the shotcup.

IF you had some "E.C. Blank-Fire" powder such as is used in GI. .30 cal blank rounds, you could do as you suggest. You could also do the same with real black powder, but it will, of course, crud up the gun something fierce!

However, if you plan on using a canister powder, I believe a wad or two is needed to give sufficient confinement for the powder to produce a "bang". I'd use Unique or a similar burning rate powder. ANYTHING, such as a wad, used to confine the powder becomes a potentially dangerous projectile, so such a round has to be fired in a safe direction. The wads would only travel 50 yards or less, though. If you used newspaper to wad the shells, the danger range would be pretty short!