Inventory shipments

What requirements do shipments of inventory need to meet?
How do I clear customs when I’m sending inventory to the warehouse in Riga or Barcelona?
Can I drop off my inventory at your warehouse by myself?
Do I have to ship my inventory to you personally?
Can I send different products in one shipment?
Does Printful ensure the safety of my warehoused items?
Who is responsible for shipments during transit?
Who has to clear customs when I’m sending inventory to the warehouses in the US?
How can I get my inventory returned to me?
What should I know about the new Smart Park fulfillment center in Riga?