So you want to send your raw metal ore away for smelting but you don’t want to wait until the next sim day to get the ingots back, right? The simple solution is to deposit the ore in the mailbox just before the mail carrier is scheduled to arrive at 8:00 AM every sim day.
It doesn’t matter what town your sim is in when she sends the ore to be smelted. In the screenie shown here, my sim just sent some iridium ore to be smelted in Champs Les Sims. The mail carrier waiting for my sim to move away from the mailbox is there to deliver the iridium ingots already.
Also, send your metal ore to be smelted while your sim is still in the adventure world. There is a chance that you’ll get back one of the magical gnomes from that world with or in place of the processed metal.