This is the latest holosheet (used on many HGSS style cards+)
Originally it was an overlay for the HGSS cards (cards created by the 2 below) Edited and changed to be rectangle and given a dark background.
Should be generally used in 2-3 layers (or more) with colour dodge, multiply and a middle one which can be anything (preferably changed to a lighter colour) to give the holofoil effect.
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Credit to the below for the original holosheet :