AITA for not giving my sister my Christmas Present?

So, I (17F) have a sister Thea, (15F), who is into art, drama, music. I like English and history, on the other hand. So my great-uncle got us a present each for Christmas, which were these cardboard animals you had to put together. I'm not really arts and craftsy, so it didn't appeal to me that much. Still, I took it home and put it safely in my room. Thea tried making hers today: but rage-quit after a fucking minute because she's like that, but then resumed it. But it didn't plan out so she threw it away in a rage. Now she wants mine so she can construct it. Though I'm not interested in mine, I didn't give it to her because I think if my great-uncle went to the effort to get us a present, Thea's wasted his money by throwing it away, so I don't want that happening to mine. So then Thea said she'd give me five pounds for it, but I declined. I already have £50 from Christmas money, and I'm extremely un-materialistic so I don't know what I'll spend £50 on.... So I don't need another £5 so I declined. So now my mum's taken Thea out to buy one, when my dad thinks I should've just given it to her. My mum seems a bit annoyed I turned down the £5 deal. I told all of them it was entitled to expect me to give up my Christmas presents and be mad I wasn't. AITA?