Well I found out super last minute that I'm going to Otakon,
So costumes I thought I would have months to plan out and execute quickly turned into about a week.
Therefore I'm kinda stressed and very short on time.
Which is why I need you guys' help.

I plan on debuting my Deanna Winchester (Dean Winchester's genderswap) from Supernatural at Otakon and pretty much everything is under control, expect for this pistol.
Dean carries a custom engraved .45 caliber pistol and is one of his distinct traits, so I would love to have it.
But I have absolutely NO idea how to make the engravings.

I have a cardboard base all cut out and made, but how will I get the design on it?
I tried cutting into a test piece of paper mache, but obviously the paper ripped.
I also tried it once it dried, but it takes a lot to cut through it.
Another idea I had was to cover it in air dry clay and then just kinda take a tooth pick and do what I have to do.
But I heard somewhere that clay doesn't stick to paper mache? (correct me if I'm wrong)
And the design is a little too intricate to do the whole glitter glue design method.

Anyway, do you guys have any ideas?
I am seriously stuck.
Thanks a lot in advance!~

TL;DR
I need to make a custom engraved pistol, but I have no idea how to make the design of the engravings. Any ideas how to execute that?

[Picture Refs]

Dean's Gun
Custom Engraved Pistol Example
My Base 1
My Base 2