I finally found one on amazon US. As I live in Europe, it was quite expensive , like 30 or 40 euros, I don't remember. Have you tried Amazon ?
Edit : here I think it is the one.
So I actually just followed this BGG thread, downloaded and printed the templates that someone else made, and I bought the Plano boxes off amazon. They are good material and feel sturdily made. I don’t have any concerns with the purchase and am definitely happy so far! Much cheaper than the inserts available and it all fits in the box with the lid just barely not closing all the way.
https://boardgamegeek.com/thread/1726878/yss-yet-another-storage-solution/page/1
4 pack Plano3600 - https://www.amazon.com/Plano-2-3600-Prolatch-Stowaway-Utility/dp/B00CKIG4NC/ref=mp_s_a_1_4?keywords=plano+3600&qid=1558362025&s=gateway&sr=8-4