Step 1 Getting on Internet
Some advise I found:
Air Float Systems (http://www.airfloatsys.com) manufacturers Strong Boxes that come in multiple sizes with different custom foam inserts. Simply call them or visit their site and tell them where you reside and they will let you know of a dealer in your area where you can pick up a box to fit your artwork. You must give them all three dimensions (length, width and depth) of your framed piece to order the appropriate sized box. Strong boxes are a patented item and can be a bit pricey but are well worth the money to deliver your artwork safely. If you can't find a strong box in your area, a Mirror Pack Box might work for you.
In practice when not in US:
Interesting when trying to order through the web; getting case of 5 strongboxes would cost around 450 USD for the size I was looking for. However...shipping it was...1100 USD. So I Continued my search for alternatives.
Art boxes for transporting framed art, in US but have asked if I can get them somewhere near Amsterdam. No answer received...http://www.airfloatsys.com
Mirror Pack Boxes:
It is highly recommended that you use a shipper who allows you to insure the art for its full value or at least the price in which it was sold. You should never ship artwork as "ground" service since it allows too much time for the piece to be damaged during transit. Insuring your shipment will secure gentler handling.
Didn't really find the right size, so then decided to take care of it myself.
Creating my own box (on the right)
After all not too complex. Materials needed:
1. Wooden box that can be opened/closed with screws (had it made by 2. carpenter, around 150 EUR)
3. Sound isolation pads
4. Pipe isolation tubes
See for the steps below
Step1: cover bottom of the box with isolation material
Step2: put isolation tubes on the side
Step 3 : wrap in bubble paper
Step 4: wrap in art bag
Step 5: Cover with Isolation pads
Step 6: Close the box
Step 7: send in style ;)
Decorated it with ink and a street art posting, so it is clear that what's inside is FRAGILE !