I searched for an answer to this question, but could not find one.
Whenever you finish a long rest, you can touch a nonmagical object and imbue it with one of your artificer infusions, turning it into a magic item.
Once my artificer achieved the appropriate level, he chose the Replicate Magic Item infusion for a Bag of Holding. This he fashioned from his existing backpack, which has a PHB weight of 5 lbs. However, a Bag of Holding normally weighs 15 lbs.
Which weight do I use for my encumbrance considerations: 5 lbs. or 15 lbs.?