Like the tittle said is it even possible to summon demons or doing spells using your mind palace having an altar and candles because I read a part of Lucifer and the hidden demons and it says “A difficulty faced by one attempting magick is the creation of a magickal
atmosphere. Without this sense of magick being real and present in the
moment, it is difficult to believe anything is happening. It is a stretch to
convince oneself that magick is proceeding in an ordinary room in your
home, by doing nothing more than closing your eyes and going on a
journey within. When you set up an altar, with plentiful sigils, the light and
smoke of candles and incense, it feels more like a piece of magickal theatre.
It is easier to suspend disbelief in this state”
It is definitely possible, you don’t really need any materials for most rituals but like mentioned they help convince your mind that it’s real so you get more immersed into it. Lots of people do direct magick through various ways in their minds and it works because they believe it’ll work. Pathworking (like the book Lucifer and the Hidden Demons is about) is another way you can do it effectively.
The altar, candles and everything else are for you, to let you get immersed into it and fully believe it all for a moment. The more you do magick and the more you do results, the more you’ll have faith and belief in your ability to do so, so it’s less needed. But magick doesn’t need to be something like that, you are a living god so the fact that you do your magic in your mind means it will still work as long as you believe it will.
Yes numerous people have temples in the Astral where they conduct magic. It can be as simple or elaborate as you like. I keep mine simple so that I can focus on the magic
You can always Evoke eninity in your mind you can even use ritual tools and do full ritual or spell work fully in your mind.
For example how would do magic if you lost you eye sight or what you lost your voice what if you lost your hands all those do help one do magic but all that is need is the mind