Hmm, makes me think about repurposing Champagne, Prosecco and Cava corks on French, Italian and Spanish bikes respectively as end plugs.
As for end grips, unless they fail/wear out very quickly, I'd say enjoy them and replace as needed.
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Larry:1958 Drysdale, 1961 Gitane Gran Sport, 1974 Zeus track, 1988 Masi Gran Corsa, 1974 Falcon, 1980 Palo Alto, 198? Vitus 979. Susan: 1976 Windsor Profesional.