OK, I would make a couple of changes. In your Proceed_Click, I would change the IF-ElseIf s to a Select Case
Select Case True
Case SizeA0.Value
Print #FileNumber, "0"
Case SizeA1.Value
Print #FileNumber, "1"
Case SizeA2.Value
Print #FileNumber, "2"
Case SizeA3.Value
Print #FileNumber, "3"
Case SizeA4.Value
Print #FileNumber, "4"
End Select
This is easier to follow than nested IF statements. Select will eval each "Case" until it finds one that is true.
I would do the same for the Length ElseIfs
Another change I made was to Group all the Size buttons together in one GroupName and group the Lengths as well under another name. (see picture). This will allow the SizeA2_Click code you have to work (Which I changed to the new group names)
As this was simplified, I couldn't test fully, but it should get you going