Check this thread, a few resources to be had. Swisspost PostPac International
I tried sending 7 separate boxes, each weighing about 15 kilograms. The price would have been about 115chf / box [company was paying for relo] With the ~3 week econonomy option, that would have been ~800 chf.
You need to goto the Swiss Post website and create a way-bill for each box, this is required by the customs agency of your destination. This webform is atrocious, as it allows for zero autofill, you cannot navigate backwards, or you break the form. So, when you make one, do it in one shot, then do the next one. Capture the resulting form as pdf so you have the thing for reprints.*
There are also small stickers each Post office will give you, about 4x3 inch labels, for your Swiss address, and you destination address.
When I went to do this I had all the forms filled, they gave me the stickers, filled those out. I had a small number written in the corner of each box, so I could match each one to the appropriate weigh bill. I slid the first box through the Post employee's little bomb proof window, and the lady begins to read the weigh bill.
The weigh bill is a customs form, and has absolutely nothing to do with them taking the box, taking my money, and shipping the goddamn thing. So, and to my oh so switzerlanded chagrin, She asks me: "Was ist oosid leenehns?"[my creative phonetics for english words read as german]
The entire form is IN ENGLISH, and she wanted to know what "Used Linens" were... She then asked what the baby items were. And then the various books and documents.
Ganzes genau was the mantra chanted, as another helpful Post lady came over: "Wir mussen ganzes genau wissen!" We must know exactly everything!
They literally wanted a description of the various baby toys and accessories, the types of books and documents, what the linens actually were. They were basically playing at being customs agents, just because they had touched the paperwork.
After trying to capitulate, it still took five minutes to get the friggin box back. I had never been so pissed in my entire time in Switzerland, Ich hatte fast postalisch gegangen [I nearly went postal
I could have presented them with a list of 25 items, with subcategories, and a written, notarized promise that it was all packed both alphabetically and by size, and they would have taken it with a smile. It might have been a box of handgrenades, but they would have had their precious list, and, I am quite certain, would have shipped it.
Either way, good luck with the escape planning.
So, because I did not have an exhaustive list of every single item being shipped, I was left with 7 boxes. These we shipped by freight with the same company we used to ship our household items. Cost 2000chf, but, well, the company ate it. Yay company.