How to make every nail polish you own double as a holographic polish for $6-15

I've posted about this before, but there's no real need to buy holographic nail polish in every shade when you can just buy a holo topcoat and use it to transform any polish you have into a linear holo. It really works. Here's are some examples:

One coat of holo topcoat (shade)

One coat of holo topcoat (direct sunlight)

See? Just buy one bottle of topcoat instead of ALL THE HOLOS. The easiest at-home dupes.