The Automagic Horse by L. Ron Hubbard appeared in the October 1949 issue of Astounding. It can be read here at Archive.org.
It figures that the first really good story I’d read in Campbell-era Astounding would be by L. Ron Hubbard. Maybe not good enough start a religion around the guy and give him all my money, but The Automagic Horse is a solid story that would certainly be at home in Planet or Thrilling.
A team of special effects expects have been grafting and defrauding Hollywood studios to get spare parts and tools to build a spaceship. The spaceship will take them to the moon and stars, and they’re gonna be rich and famous… someday.
They get hired to make a stunt horse so that the SPCA won’t be all over the studio for a scene in which a horse has to kick down the door of a burning barn. This may be the job that will finally put them over the top with the funds that they need to finish carving out an underground workshop to test gamma rays… except the studio sends an accountant to keep track of the funds and audit their past projects!
To make matters worse, she’s a no-nonsense dame intent on seeing that the studio hangs onto every penny of their investment!
The team tries to keep the accountant busy and distracted while they build a robot horse, stuff it into the skin of a famous dead race-horse, and even use the critter to scam a guy out of thousands of dollars by racing it against several of his best horses.
Things get messier and messier as the accountant begins to account for more and more of their misappropriated equipment and the guy they hustled insists on buying the horse from them. They only have a narrow window of time and a narrower margin of error to squeeze what resources they can out of the production, and they risk losing everything.
Automagic Horse is a great example of the SF subgenre wherein enterprising and clever fellows with a knack for invention use it to try to get rich and bilk fat-cats. It’s easier to forgive the entrepreneurial underdog for their slightly-less-that-above-the-boards methods to get ahead and pursue their dreams.