How to find every possible combination of cells using VBA

Question

I am currently working with VBA in Excel and I am trying to create a code that will allow the user to select the number of columns with unique data, and then it will ask them to select the range so that it can figure out the number of possible combinations and print those into the correct columns. I have already made a code that can do this for a limited number of columns, but I want to make a generic code that can do any number of columns based on user input. Here is my original code.

Sub Every_Combination()

Dim c1() As Variant
Dim c2() As Variant
Dim c3() As Variant
Dim c4() As Variant
Dim c5() As Variant
Dim c6() As Variant
Dim out() As Variant
Dim j As Long, k As Long, l As Long, m As Long, n As Long, o As Long, p As Long


Dim col1 As Range
Dim col2 As Range
Dim col3 As Range
Dim col4 As Range
Dim col5 As Range
Dim col6 As Range
Dim out1 As Range


Set col1 = Range("A2", Range("A2").End(xlDown))
Set col2 = Range("B2", Range("B2").End(xlDown))
Set col3 = Range("C2", Range("C2").End(xlDown))
Set col4 = Range("D2", Range("D2").End(xlDown))
Set col5 = Range("E2", Range("E2").End(xlDown))
Set col6 = Range("F2", Range("F2").End(xlDown))

c1 = col1
c2 = col2
c3 = col3
c4 = col4
c5 = col5
c6 = col6

Set out1 = Range("A3", Range("F3").Offset(UBound(c1) * UBound(c2) * UBound(c3) * UBound(c4) * UBound(c5) * UBound(c6)))
out = out1

j = 1
k = 1
l = 1
m = 1
n = 1
o = 1
p = 1

Do While j <= UBound(c1)
    Do While k <= UBound(c2)
        Do While l <= UBound(c3)
            Do While m <= UBound(c4)
                Do While n <= UBound(c5)
                    Do While p <= UBound(c6) ' This now loops correctly
                    out(o, 1) = c1(j, 1)
                    out(o, 2) = c2(k, 1)
                    out(o, 3) = c3(l, 1)
                    out(o, 4) = c4(m, 1)
                    out(o, 5) = c5(n, 1)
                    out(o, 6) = c6(p, 1)
                    o = o + 1
                    p = p + 1
                    Loop
                    p = 1
                    n = n + 1
                Loop
                n = 1
                m = m + 1
            Loop
            m = 1
            l = l + 1
        Loop
        l = 1
        k = k + 1
    Loop
    k = 1
    j = j + 1
Loop

out1.Value = out

End Sub

This works for a finite amount of data, but I would like to be able to use this for any sizes of data without having to edit the code. Currently this is what I have for my new code, but I am a bit confused on when to use "As Range" and how to use them in my "For" loop.

Sub Test()

Dim i As Integer
Dim c() As Variant
Dim col() As Variant
Dim out() As Variant

Dim UniqueColumns As Integer
UniqueColumns = Application.InputBox(Prompt:="Enter the number of unique columns", Type:=1)
ReDim c(1 To UniqueColumns)
ReDim col(1 To UniqueColumns)

For i = 1 To UniqueColumns

    c(i) = "c" & i
    col(i) = "col" & i

    Set col(i) = Application.InputBox(Prompt:="Please select a range with your Mouse to be bolded.", Title:="SPECIFY RANGE", Type:=8)
    c(i) = col(i)

Next i

End Sub

I appreciate the help!