With the release of Ron Cobb's designs from The Last Starfighter and a few photos (finally) from the film, this elusive prop can at last be reconstructed.
I think they reversed the design: the top of that Truth Serum prop is now the bottom of the gun...if that makes senseI have to say, this is a bit confusing. Considering the differences in appearance, these pictures make the blaster look both the same and different. The design looks exactly right, but the scale looks way off.
That's why our quest to replicate props from pics caps are, at best, a game of unknowns I have long hands, so it shouldn't be an exact measurement to gage the size of that prop. The actress is small in stature, therefore small hands.The orientation looks right as the trigger ring is still near the index finger, but that would mean that Jane Badler's hands are tiny and Marc Singer's head is on the small side.