All you need for evocation are the sigil (or seal if you want) and enn of the entity you wish to call upon.
The rest are just tools and their presence is either symbolic or used to put you in the mood as folks have already pointed out.
These are some threads that may help you.
There are many more threads like this, that you wouldn’t have difficulty finding if you had used the search function. Please do that from now on, before posting something
