This is something that's been addressed on most of the sites I've been a member of at some point or other.
The only solution, really, is for someone to write an answer. For this you have two options
- Ping the commenter and encourage them to write an answer.
If the person who wrote the comment seems disinclined to do it (say you wait a day or two and they don't write an answer), feel free to write it yourself. Now, it helps if you are familiar with the subject and feel comfortable asserting that the answer is correct.
- Just write an answer.
You don't have to give them the chance to write an answer - they should have done it long ago, so you're not "stealing" if you actually do the work.
That being said, we don't want to just blindly transfer a comment to an answer without any supporting details -links, examples, etc. There's no way to attribute the answer to the person who wrote the comment (other than linking to the comment) so they won't be the one affected by any reputation gains or losses due to the answer's quality.
So, in the case of that question, feel free to poke Matt about posting his comment as an answer if you like. But you can also feel free to just answer the question yourself. Explain that it's a stamp and maybe even do some research to find a couple of sites that make custom stamps as an example.
And, when you're done writing your answer, feel free to flag the comments as obsolete because now there's an answer!
As Erica noted in the comments, which option you start with probably depends on your comfort with the subject and how active a user made the comment. Someone who hasn't been seen in months and just has enough reputation to comment probably doesn't need to be pinged but a user like Matt, one of the top users on the site, should be around and will be more likely to write a full answer.
