Pricing that will help all makers and artists in the future:
Consider what your daily rate is. What do you need to pay all your bills, cover materials, power, everything?
Most are between $200 - $500 per day. And as you master your skill, shift that rate upwards.
Now take that daily rate and consider how many of those boxes you can make in a 6/8/10 hour day. If it would take you a whole day to knock out one (minus waiting on drying time): use the full day price. If you could make 2, then half it. If you could make a hundred, then there’s your formula for pricing.
There you can compare an hourly rate + material cost and adjust up as needed.