Suppose initially I have a list that looks like

`list1 = {A, B, C}`

where the elements A, B, C are all matrices. I want to substitute all the three elements by list1 itself

`list2 = ReplacePart[list1, {i_} -> list1]`

which gives me something that looks like

`list2 = {{A, B, C}, {A, B, C}, {A, B, C}}`

And then, I want to do this another time, substitute all elements in list2 by list1, then I say

`list3 = ReplacePart[list2, {i_, j_} -> list1]`

Eventually, suppose I want to do this for 10 times. At the end of the day, I have to write a list of 10 local variables

`{i_, j_, k_, l_, m_, n_, ...}`

My question is, how to define the index list of local variables as arbitrarily long? So that I can just tell Mathematica the length of the list and I don’t have to write them out explicitly.

Thank you so much!