MC Enterprises makes chromed plastic caps, and they hold up very well. I have some of them on my valks from many years ago and past bikes.
The kits used to be per bike (with assortments), now you chose sizes you want.
They don't have the snap caps that fill allen bolt heads (like risers).
scroll to kool kovers
http://www.mcenterprisesusa.com/products/search/dsp_searchForm.cfm