The weight will be printed on the label that the PO sticks on the box, Once you give them the box and they print the label to get the weight on it they are not supposed to give it back for you to do anything to it, You could be damaging it and they would be liable up to the $50 insurance that is included.
I had to get the CAUTION HEAVY stickers at the counter, They do not have them out where you can just take them, You have to ask for them.
It is more fun to post the weight here so that we can watch it grow and shrink as various items are added or removed. Just do not try to equate weight with value, a given part could be very heavy and not worth much or a part could be very light weight but be very expensive.