Not really holograms, but mp4s with special effects to make fake holograms --particularly when projected on glass.

I was going to do it last year, but it was too pricey for a marginally decent projector.  This year, the price was half. 

It's on the glass front door.

Ghostly Apparitions Trailer on Vimeo
https://vimeo.com/210672018

fun!  I hope I see some of these tomorrow when trick-or-treating with the kids.

I just spent $15 for 3 scenes of zombies clawing at the door. hhh

It's good enough that Louise gets shivers watching it.

Those are really good.  What do the projectors use lasers?

>laser

No, it says it's LED. It's pretty crappy, IMO, but it gets this job done cheap.

Only 3 components

Projector currently has a coupon. My delivered cost was $71.  Be forewarned, the UI is extremely clunky.
https://www.amazon.com/gp/product/B07DDF58XM/

https://www.amazon.com/gp/product/B01K32HS6S/
I later added 3 zombie scenes downloaded from their site.


2 yards of fabric for translucent screen on glass
https://www.amazon.com/gp/product/B006ZE2OZY/