Hi,
i made something similar a while ago,
for about ten NZ bucks,thats five America dollars. not including the use of a projector.
i used a fogger "a ultrasonic water vaperiser"
and using a small motor with a fan blew the fog through a slot and projected the face of Mr Data onto it, i do have some film of it, when i can get my vid editing software working again i'll post something on youtube.
" maybe you could blow it down from the top of a door,
you could make a Star Gate to walk through, safly arriving one step from where you stepped from [

] "
bye for now and be well

:]