Hot answers tagged compatibility
Is it possible that you are thinking of this goblet (2343)? This part was fairly common, and it was introduced around 1985, so it was probably in your collection. 1x1 round plates attach securely to the top as shown in this lamp from the Pet Shop:
I still have cups and 1x1 round bricks from the late 70's and I can ensure you these were never brickable like you suggest. In the 80's, another popular build from Lego was composed of a transparent cup on top of a transparent minight head. Here is a colored example of that build.
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