Open Nintendo eShop card properly?

Who has a trick how to properly open Nintendo eShop cards? With 2 cards, the code has become illegible when opened. The cards are made of cardboard and break very quickly when opened, although I was very careful. At e.g. Steam cards is the code on a plastic surface so you can easily open it with a coin.

Unfortunately not, but tip for next time: If you have Paypal, buy the cards as digital coupons, so you bypass that.

OK thanks. Unfortunately, I do not have Paypal. Find somehow already disappointing of Nintendo that the cards are so cheap and I have problems only with these credit cards.

Did you edit those with your knife? I recommend things that cost the money to be a little more cautious. My son is 7 years old and has never had such a problem until today.

I just use a coin and scratch the code.

Nope only with a fingernail.

That's what I did on the 1st card, which just destroyed it.

Moin again. I just opened a card myself. Under the field is a hard hard layer.