Finally received the "precision" (0.5%) capacitors I ordered from Russia. Digikey and the other online shops don't carries anything lower than 1%. The only place where I found some 0.5% cap was on ebay from Russia or some other Eastern Europe countries.
They are all polystyrene capacitors from 0.5 uF to 0.01uF. Also got a 158pF.
So after spending quite sometimes measuring each caps with my LCR meter, I decided to use them to build 2 decade box (158pF to 1uF). To avoid stray capacitance and hopefully keep precision, I did an extravagant usage of Teflon
Teflon washer on the binding post, Teflon wire, Teflon heat shrink on the capacitor leads and a ceramic switch (did not find a switch made of Teflon
).
I just need to label the front panel "Wolfgang style" (mica sheet and spray adhesive) and I’m done!