It's my 18th birthday soon and I have relatives asking what I would like for my birthday. My issue is that I already have a lot of stuff (so not a lot of space + I've already got most things I want for myself) and there isn't really anything I want right now. I would rather have money so I could decide to buy something I know I would use or wear further down the line, I have a feeling that if I don't ask for money from my grandparents they'll end up buying something I can't wear or use like jewellery or other random items since they have a habit of buying a lot of random things for me and their other grandchildren

But I'm worried in case this is a rude thing to ask, I really don't know if it is. I've been going back and forth about this for a while now, I'm worried about coming across badly or rudely or anything along those lines.

Do you think it would be rude to ask for money instead of another item for my birthday?