also: しせいハガキ
noun
private postcard; unofficial postcard
A postcard printed by a private company or individual, as opposed to the official government-issued postcards (官製はがき). Used for personal or commercial mail.
年賀状は私製はがきを使ってもかまいません。
You may use privately printed postcards for New Year's greetings.
この私製はがきには切手を貼
You need to affix a stamp to this private postcard.