[Sundae]

Right.
Have decided. Surprise surprise, it's both.

Will accrue a stack of dollar bills between now and December, to make the pizza.
But will fold an English banknote onto a card in the shape of a shirt. With the tagline "I know how much you love clothes."
Not blowing my own trumpet, but I can sit quite happily and fold a shirt from a receipt, a bus ticket, a discarded lottery ticket. It's a really simple fold in the end.

Now I have to master a heart, to make a banknote card for my niece.
May use a Euro note for that, not sure how low they go. It's a token gift as I already have a personalised present for her 21st (end of September). But the card will be hand-made, unique to her and also carry the cachet of money, even if it's actually cheaper than a Hallmark card.