So instead of the current selection between do+bd, es+bd, do+es and unbound magic, have a ticket purchasing method where you select how many tickets you want which unlocks a tier of fluctuating mass containers for each tier (maybe up to 6) which requires 25 tickets for each category (do, bd, es, unbound magic) but you can buy 1 ticket for 1 unit of those items, and any uneven amounts between tiers (25, 50, 75, 100, 125, 150) rolls a chance to unlock the next tier so 46 do will have a chance to unlock the 50 ore grade mass container. This would help with uneven amounts of ore