Stainless Steel "Wet Sand" rule?

My father just got promoted to Conductor in a small railroad club he volunteers at. As such, he's now looking to get a key for the club's old (1920s, IIRC) caboose. He can buy a new key online (they're modified skeleton/lever-lock keys, nothing fancy) for ~$100. However, I said I would look into getting him a key 3D-printed that has a customized handle with the railroad club's logo and his initials embossed on the handle of the key.

Here's a few pictures of the key.

Some important dimensions:

• The end of the shaft is .243" in diameter and is .81" long, not including the dimpled end.
• The protruding part of the key is .51" long, and tapers out from .125" to .275" head-to-tip. The steps range from .217" to .349". The two pieces at the very end are both .127" by .275" by .09"

Seeing as how the only metals SW offers are sterling and stainless, and sterling silver would likely snap off in the lock, it looks like stainless would be the best choice for printing.

However, the "wet sand" rule of thumb makes me worry that this would break during the mold-making process.

Would making a near-duplicate of this key (with a slightly different handle) out of stainless steel be possible?

PS: I know this might seem legally shady, but trust me, he has authorization to have another key made. Don't worry about that part.

As long as you maintain the minimum wall thickness, you should be fine, The key for the wet sand rule is that overhangs may sag during production. If the center of the key is hollow, as some skeleton keys are, it may come out a little oval in shape.

This is most certainly not hollow, so I doubt that'll be an issue. The protruding part of the key needs to be fairly exact, though. Will it likely deform during creation?

Also, another question - the locks on the caboose are old (and thus, in sorta bad shape). Unlocking them requires putting a small amount of extra force upon the key. Could the method in which the key is made cause it to be at high risk of snapping in the lock?

Being thick it will deform less. The stainless is infused with bronze, so it's not as strong as solid stainless, but I can't say whether or not it will break the lock.

Some of the real (old) keys are bronze, so I imagine stainless+bronze would be OK.

What amount of deformation would be expected to occur? My dad says the locks probably won't open if the key differs by more than a couple hundredths of an inch.

One possibility for you might be to model it with slightly extra material and hand finish to a more exact size. Your Dad's estimate of a few hundredths is probably true.

According the the guidelines, the accuracy is ± 2mm. Free ranges suggestion is a good one. May be more cost effective to print in a more accurate material and have a mold made to cast it.