So far what I’ve tried is the following…
At the most simple, I’ve used a triangle with Hekate written on each side of the triangle.
(At times I’ve incorporated my own personal sigils on the three points of the triangle where I usually place tealights)
A step up from that has been incorporating the universal circle…
If you watch Connor Kendall’s videos he uses a smaller universal circle for evocation.
I put the universal circle in the center of the triangle, with He-ka-te’s name inside the points (like what is normally done with Mi-Cha-El), and the taking a page out of mark Alan smiths work, I’ve used the rest of his hekatean triangle of art from “Queen of Hell”. That was my standby for awhile.
I wanted to mix it up and try something different though and found the Azazel triangle of manifestation interesting.
So I again used the universal circle in the center of the triangle, but with the addition of the “Seal of The Sorcer” from kingdoms of flame (have not gotten or worked through that book) in each point of the triangle with Azazel’s name going around. Because the UC is based on the SotS, and Azazel is a big part of all that so it only made sense to me to put it all together. I thought about putting the names of the three demons involved in the SotS and UC around the triangle (Azazel Fastos, I don’t remember the third one) but didn’t.
Activating that was an interesting experience…
I blooded the inner UC and started to chant the grand conjuration while simultaneously playing this video:
I eventually saw the center of the circle flame up and burn away so that there was a dark portal or hole.
Then I felt an energy I would describe as shifting sands and my vision matched that energy staring into the triangle as I started to trance out real hard.
Shit was intense, and really cool 
(It’s really good for servitor creation as you evoke them into it, Azazel being associated with metallurgy and blacksmithing, it only makes sense that you could use this triangle as a manner of “FORGE” for things, cuz why not?)
Edit:
Recently I’ve contemplated how I might go about making a triangle with Lilith, and Lucifer or Samael (or just all three) incorporated into it.