The situation with shipping right now is not too bad. Things seem to be working well at present. If you are careful and ship intelligently. Here is how it shakes out.

International carb rebuilds
These days I do far fewer international carb rebuilds. There are a couple of important reasons, but easily the most trying is the situation with international shipping. USPS used to work, but now it's incredibly bad. Dismal. And they can be even worse when you ship to me, because your country's state mailing service likely links up with my nation's embarrasingly poor service and that is a disaster. If you are outside the US and don't want to use either FedEx International (preferred) or DHL, I'm sorry, but you should't send me carburetors.

How-to books
I used to ship booklets USPS Priority but now booklets go out USPS ground rate. During Covid certain countries returned all my booklets while others lost and delayed them. Now everything seems back to normal. While the USPS organization has proven to be easily overwhelmed, booklets appear to be within their capability. At least for now.

Carburetors
All carburetors are returned to you using FedEx. Large, heavy, expensive boxes is their forte. I don't use UPS and I don't use the Post Office (USPS). Don't trust your carbs to USPS.

USPS
Why? Aside from the fact that USPS seems unable to deal with valuable cargo, they do something else that should make you think hard about relying on them. They simply do not take responsibility. Whether for domestic or international shipments, starting a claim will get you nowhere. Worse, if the lost shipment is international, they will throw up their hands and suggest you contact US Customs. As far as I know, US Customs does not have a customer service department.

Boxing
About every tenth carburetor shipment I receive has the carbs poking through the box, and twice as many are in boxes that arrived only by a miracle--tape loose, cardboard old and decaying, and little to no stuffing. Your box should be at least three inches larger than your carburetors in every direction. Reinforce the inside bottom and sides of the box with extra pieces of cardboard, carboard wrap delicate areas such as throttle cable brackets and float bowl overflow nipples, and fill the space with crumpled newspaper--after bubble-wrapping your carbs. Do not use metal or plastic or wood boxes. This is counterintuitive. Unless they are large enough to allow the necessary padding around the carburetors, your carbs are just as likely to get banged up in a metal toolbox as in anything else, and probably more.

Bubble wrap
Use the large bubble. Small bubble wrap is for very lightweight objects. Ninety percent of people use bubble wrap incorrectly. It should be wrapped around the carburetors, not stuffed between them and the inside of the shipping box. Use it for what it was intended for and works best for. Bubble wrap is also way too expensive to use as stuffing.

Any kind of styrofoam
Myself, and others in my business, dislike finding styrofoam--especially peanuts--inside the bix. The stuff is difficult to get out of my workshop and even out of my driveway. And it isn't designed to support irregularly shaped heavy items such as carburetors. Avoid using it please. I did once get a shipment packed with real peanuts. That was interesting, though I don't think it was any better a method.

Insurance
UPS and FedEx both offer $100 of insurance at no extra charge. You can add to that, but with FedEx, if you exceed $499, this will make the shipment automatically signature-required. I don't mind, really, but you will when your carrier tells you the carbs were undeliverable because I was away from the shop for a moment.

Checklist
Please always include the shipping checklist. It's foundational for the good communication that doing our project together requires. Print legibly. It can be difficult to tell the correct return shipping address when it is hurriedly written.

Assignment of extra fees
It is really bad form for you to make me liable for additional carrier fees. How do you think it feels for me to get a bill from a private carrier long after your carbs have been completed and returned to you?