Simulating the Kastle-Meyers Blood Test

Hello  Scientists!

I’m setting up a crime scene that has “bloody” evidence -- shoeprints,  knife, etc. (The ‘blood’ is simply red paint.).

I would like the team members to perform a Kastle-Meyers test on the ‘blood’ … some coming up positive (pink), others negative for the presumptive test.

I’ve purchased synthetic blood (which isn’t necessarily cheap, and has a limited shelf life once opened) to which I can apply on top of the paint and get the pink reaction using phenolphthalein and hydrogen peroxide.

Question: What inexpensive chemical (solution) can I apply on top of the red paint to get the same (pink) reaction? (That chemical would need to be translucent or red so as to maintain the red color of the paint).

I’ve read Wiki page on the K-M test and it says ‘chemical oxidants such as copper and nickel salts will cause the Kastle–Meyer reagent to turn pink before the addition of the hydrogen peroxide’.

So it seems I could apply a water and copper/nickel salt solution on top of the paint to get this reaction.   If so, okay … although it’s not ideal, since that apparently gives the pink reaction PRIOR to the Hydrogen Peroxide drop. I would like the re-action to happen afterwards. Would anyone know what precisely to apply to my paint to simulate pink reaction AFTER the drop?

Thank you kindly for anyone’s support!

David