We are a company operating out the US that offers a wide array of antique and modern items from around the world. We have a warehouse in Thailand that houses the majority of our products and services the Asia region of the world. Their website is outdated, as is their inventory system and we do not have the weight of a majority of items. We also are not sure how to calculate shipping even if we did have the weight of every item. Some items we have are quite large and heavy and will not suit standard shipping, especially out of Thailand. If a person wants an item from our website that exists in Thailand we have to pack it on our next shipment, bring it to the US then get a quote to ship it from here to another part of the US, or if it is local, deliver the item ourselves. As I said before some items cannot be shipped via standard shipping so it either has to be shipped via freight or a third party service. Because of this, the varying weight, price and location of pieces we are terribly confused on how to set up our checkout and shipping system. We cannot offer a flat rate for shipping because of this either, and customers cannot actually purchase anything without a shipping method. If possible we'd maybe just like a disclaimer at checkout that tells the customer that shipping will have to be calculated after purchase and to contact us about it, if the piece they are buying is something we do not have in our US location or if they are not in our area for local delivery.
I hope in your case if you are able to add multiple warehouses, the shipping process would be easy. I would suggest you check out the Multi Carrier Shipping Label app that helps you handle this with ease.
With the app, you can add multiple warehouse locations (US & Thailand) and set up shipping based on these locations. Now, based on your customer location, you can handle the shipping process. You can add your own carrier accounts and the live shipping rates will be displayed at the Shopify checkout based on the product weight & dimensions, customer locations, and other factors. The app also helps you ship freight items as some of your items are heavy. For any help required with the setup, you can contact our support.