What does "make [someone] into shoes" mean?

In BBC's Sherlock series (Series 2 Episode 1, "A Scandal in Belgravia"),

Jim Moriarty says to Irene Adler: "If you have what you say you have, I'll make you rich. If you don't, I'll make you into shoes."

What does he mean?

Googling led me to a link that that is probably enlightening, but unfortunately, not for me.

So if this is a play on words, then what are the possible meanings?

Expensive shoes are made from leather. Leather is tanned hide. Hide is skin. Making shoes from Adler is a threat/promise that Moriarty will skin her (i.e. remove her skin, probably while she is alive).

It's not a play on words, but Moriaty is being playful here. The fun he's having is in the repetition and juxtaposition of the snowclone "If you X, I'll make you Y".

For purposes of threatening harm for being deceived he could just as easily have said "[...] I'll bake you into a pie", which in context with the preceding statement is a clumsy rhyme without the poetic juxtaposition.

While the literal meaning can be taken as to skin alive, I suspect Moriaty is being metaphorical here.