I'm determined to run this portfolio for decades, so it's best to keep it as simple as possible.
If one of my fellow Germans on this board has further suggestions (specific ETFs, taxation, etc.), I'd be more than happy to reconsider, though.
Considerations.
1) The future of the EUR is a wildcard. I don't wanna put all my savings into the Euro area, for no other reason than being born here.
2) Nobody knows who's gonna perform well ten years ahead, Europe or USA. At present, USA leads, but that can change easily.
3) I have zero trust (I have some trust issues

25% Cash in a government-guranteed savings account, yield 0.5% at the moment (EUR)
25% Krugerrand coins in a safe deposit box (GOLD)
25% US 30yr bond A1ZSHE, maturing 2044 (USD)
12.5% DEKA DAX30 ETF, paying out, TER 0.15%, full replication, automatic taxation by the custodian bank
12.5% DEKA MSCI USA ETF, paying out, TER 0.3%, full replication, automatic taxation by the custodian bank
3/8th of the portfolio (Cash & DAX) are EUR-dependent.
3/8th of the portfolio (30yr bond & MSCI USA) are USD-dependent.
2/8th of the portfolio are GOLD-dependent.
The only high-handed assumptions baked into this are that the 30yr USG bond is the ultimate flight-to-safety destination in deflation (meaning that EUR bonds are less credible in terms of safe haven status).
And that German DAX will have a better long-term performance than say Greece & Italy stock indices.
(I have to add I actually dislike & distrust stock markets, buying stocks at today's valuations will be the most difficult part for me in setting up the Permanent Portfolio).