What to buy a 15 year old Groomsman

I was going to suggest a gaming voucher. Something he can buy games with or save towards upgrading whatever box he has. Is there noone you can ask about what else he's in to? Cinema pass. Day out paintballing, gokarting etc, personalised skateboard. (bad examples but you get my drift). Maybe something to cover him taking a friend with him. If he was a bit older I would have said an IOU for a couple of driving lessons.

You could give him an amount and ask him to make a wish list. You know you're buying something he wants and he gets a surprise as to what he receives still.

I dont see why a hip flask is inappropriate, if he doesnt drink yet he will in a year or two... I got a cocktail shaker gift set at 15 (a year before I even started drinking) and no one thought it wierd

to me a gaming voucher is a perfectly fine gift but unlike a hipflask its not really a keepsake, the game will go out of style/get finished quick and then probably be traded for 1/30th its price at CEX or somewhere

I would also avoid knives, he maybe a very grown up 15 year old but I wouldnt take the chance as he would only have to get caught with it in public to possibly get a criminal record. Other keepsake items include pocket watches and cigarette boxes (although if he doesnt smoke which he shouldnt at his age then that would be useless)

could you get him jewellry maybe, like a dog tag style or something or a leather braclet with engraved metal plate like this

A leather initialled wallet?

Engraved collar stiffeners?

What about a watch, our sons will be 12 and 17 and I've got them a watch each. Something useful that they can keep x

We've just got my 2stepsons (19 + 16) and our 2 boys ( 10 + 5 ) (ushers and pageboys) engraved pocket watches, it's something they'll always have a little keepsake

Thanks for all the suggestions. I forgot to put my budget was £10. I already have a few gifts that they all can have you see. I would think a hip flask is fine but me and his mother (stepmother) have a bit of a difficult relationship and am not that close to my dad either, I would feel I was rocking the boat a little bit. I don't speak to my brother much as we so far apart, plus the awkward teenage years and he talks more on the xbox with my fiance. My sister said he won't wear a watch because he has his phone but she thinks he would like a wallet.

A nice wallet engraved I think is age appropriate.