The ultimate set consists of 
Manual
Permit for use of radio
Warning tag
Manual and Permit can be ordered on eitehr white (like new) of manila (looking old) paper.
 
THE MANUAL
Reproduction of 4-page long users manual for the radio. Historically accurate! Add this convincing detail to your precious Volksempfänger! Manual is in its original language - German.
 
THE RADIO-PERMIT
Two-sided A4 document certifying you're allowed to use the radio and paid your dues. It comes pre-stamped and signed. To fill out are:
your name and profession 
address (city, street, street number)
period for which radio-fee was paid (recommended November 1940 to be consistent with the stamp below)
name of the post office (recommended Berlin 8 for the same reason as above)
strike through "fur je 1 volles Kalendervierteljahr (you will pay monthly)
Check the top edge of the certificate - it's where thr piece for Post Office was (torn off before given to you) - accuracy of this reproduction is just stunning!
 
THE RED WARNING TAG
In 1941 a campaign has stated for NSDAP Blockleiter to visit all households with a radio and attach red warning sign to them. It wasn't very popular apparently and few of the original tags remained to this day. Warning says that listening to foreign stations is a threat to security of the nation and will be met with sever punishment by the order of the Führer.