Okay what is a sap cap?
Why it's a simple cap with a pocket of lead shot sewn into the back lining as a suprise impact weapon.
At most places of purchase they run approximately 20 bucks plus shipping.
And from everything I've read the 'unique impact material" is just a poorly sewn in pocket of lead shot likely to break upon the first hit.
We can do better than that.
What I had:
My trusty baseball cap.
Athletic tape from the Bracers build.http://www.blogger.com/img/blank.gif
A heavy needle and thread I think I got from my mother years ago.
What I bought:
Fishing weights. Egg sinkers for $1.50.
Okay, first up: take the weights, remove from bag, and line up in a neat little row on some athletic tape, then tape up into a tight little bundle. You'll want it fairly thick as we'll be sewing this bundle directly into the cap lining through the tape itself.
Pull the lining of the cap down and place the bundle of weights inside center.
Proceed to sew the bundle to the lining. Since it's being sewn into the inside lining, stitches will not be visible on the outside of the cap. Also, by sewing the athletic tape bundle directly into the lining, it is more secure and it should stand up to several blows without coming loose. We've slammed mine at least a dozen times into a metal table and desk and it's still nice and tight in the lining.
Fold up and you're ready to go.
The bundle will show, at most, as a long barely noticeable lump on the back of the cap. Fair trade off for the power that it has in that small bundle.
You can also sew the lining down tight to the back of the cap after you're folded up the now sewn-to-lining bundle for an extra secure fit, but it will leave stitches showing on the outside of the cap. Not a big give away, but something to consider.
This thing is a last resort weapon only, but it is a lethal little package.
IT IS NOT TO BE TAKEN OR USED LIGHTLY.
The weights I have in my cap will, I have no doubt, crack a skull and break handbones.
They're heavy and the swing just amps that up even more. You will do damage to anyone you solidly hit with this.
It would be best, IMHO, as a surprise weapon. Let's say you're at knife point being mugged:
Act fearful, give into what ever the guy says, place your hands in front of your face in 'fear' or hold them up to show you're not a threat.
When you decide you have a chance to act, it's a simple thing to grip the bill of the cap and flip it into the guy's face or hands. Hopefully you'll break something on him. Either way it's probably best you RUN LIKE HELL while he's distracted.
If you can't get away then you had better be ready to back up the initial surprise hit with something else or you're going to get hurt or dead. USE YOUR OWN JUDGEMENT. I can't do it for you as every person and situation is unique.
Get some training. Then keep training.
The sap cap is probably a one trick pony: it's a useful surprise when you have no better options suited to your survival situation.
My cap is very heavy. It's likely other people will want smaller weights or actual lead shot (emptied shotgun shells or refills should work fine.) Mine is OVERKILL and it will hurt and possibly maim when it hits someone. As with all these projects it's pretty much a 'proof of concept' design. I might possibly use smaller weights or even the lead shot in the future. For now though, I like it. :)
Legally, it's a very shaky thing. I do not believe this falls under most accepted 'sap' laws. However these homemade things are always shaky like that. However, if you have no choice and it's you and your loved ones or the other guy who's holding a knife against you, do what you have to do. Do what you have to do to get home alive in your best judgement of the situation be that hand over your wallet or smash the guy's skull in. Do what you have to do to save yourself and your loved ones, this isn't a game. Use some good tactics and judgement.