But personally, I would draw the line at one-of-a-kind or extremely rare cars. That's why my fleet of over 40 PFE reefers does not include an aluminum car.
I like the d20 method. If you roll a 20, pull the aluminum reefer out of its box, put it on the layout for that session, then put it back in the box at the end of the day. Next time you roll a 20, pull out the UP ARA box, or the RF&P stock car.
