I already put together an AR pistol w Adams Arms 7 inch piston upper. It's my home defense weapon along w my EDC Glock17.  

Now, I want to do the same with a ....

10 inch or shorter AK in 762x39
EVO scorpion
MP5k

Where can I get the end plate for these weapons that fits the Blade Brace?
I prefer side folding brace adapters.

Any other short weapons I should consider for a Blade Brace?

For the scorpion you can get the adaptor for a AR carbine tube. I think they also still come with the tube. Go to the CZ USA webstore for the adaptor that comes with the tube.  CZ Webshop
Found it.
Link to adapter with tube.  

Now as for the Scorpion vs SP5K.
I wanted a MP5K PDW SOOOO BAD!!!!
I went Scorpion instead of MP5 because it was cheaper and easier and overall more plug and play to get a brace adaptor for me to play with and see if I wanted to go SBR.
Also the CZ website in the post above has all the parts you will ever need Its amazing the parts they have to sell. You name it they have it. You could rebuild just about 85 percent of the gun from the parts available on the CZ webstore.

MP5 is not like that. HKparts.net and a few clone manufacturers.

Now with the HK SP5K and I wouldn't hesitate to go MP5 SP5K with a Kak Brace.

cnc warrior might have something for the ak.

I built my AK-105 type pistol using a 4.5mm side folding trunnion and a JMac Custom Mod 2 stock adapter. Allows it to fold, but it will not fold enough to really make a difference. I'm building a second AK pistol that will use an AK-Builder modular rear trunnion that allows the use of ACE pattern attachments. That should allow a completely folding brace so long as I don't install a left side optics rail.

Sexy