Item Marking

I need a way to mark items with an printer on an uneven surface. I just need to create an ID and date (prefer a QR code if possible). The surface itself if relatively smooth, it is just curved (like a ball). Can someone just point me in the right direction? This would be a HUGE benefit to my project if this could be done.

There are many different laser markers/engravers available.

How big is the area you want to print on?
What is the radius of curvature?
Can you move the surface so that the element to be printed is always close to the print head?

A diagram or photo of the thing you want to print on would be a big help.

...R

Unfortunately, the shooting fraternity have polluted google somewhat, but the search term is, I think, "ballistic printer".
Manufacturers like Domino and possibly Brother produce these for printing on things like cans and eggs on production lines.

If the degree of curvature is not too high you could print plastic sticky labels that are compliant enough to stick to the curved surface. I know the Brother P-Touch TX labels are thin and flexible.

EDIT: As a side note: I have put P-Touch TX labels on hundreds of keys (brass and nickel-plated) over the last 7 or 8 years and not one has fallen off! That's good adhesion!

http://www.trendmarking.com.au/portable-inkjet-pen-printer

Only for porus surfaces though.
Ones using inks for plastic are 4 X the price.

In former times [tm] pad printing was used for that purpose. Color is put on a flexible pad, which then is pressed onto the uneven surface.

DrDiettrich:
In former times [tm] pad printing was used for that purpose. Color is put on a flexible pad, which then is pressed onto the uneven surface.

Seems to me that on a past episode of “How it’s made” or something like that they showed that was the way they printed on golf balls for the logo etc with a way to rotate the ball against a pad with the information on it.