I’ve actually made demon jars.
Needed component vary.
First step is obtaining a jar, second step is picking the demon. Then you fill the jar up with things which are attributed to that demon.
Like the gemstone or crystal it’s tied with.
Like it’s favourite incense, any herbs associated with that demon too.
Find out what planet and element it’s connected too, then use herbs and other magickal items connected to the demons planet and element.
Create a sigil of the demon anoint it in blood or semen or both and open it and charge it, then place it inside the jar.
You can also place planetary squares which are connected to the planet the demon is connected too inside the jar.
Next obtain cloth or material which is in the colour which is connected to that demon around the jar.
Then seal the jar, consecrate a candle with the energies of that demon. Make a small incision on the jars lid then place the candle on that.
At the bottom of the jar draw it’s sigil in marker, open it on the outside of the jar and seal the jar using your blood.
Light the candle open the flame as a gateway, you can even use the jar as a vessel, you can summon the demon and place it inside the jar.
You can even use it not only as a vessel but can incorporate it in a candle spell, it has many more uses.