Rather than clog up the Animal Crossing thread - I'll put this stuff here
Amiibo's are normally small plastic statues made by Nintendo and designed around their characters , however they also have an NFC (near field communication) chip inside of them which can be used to unlock things in certain games based around that character
As these are fairly basic people worked out how to extract the codes for these and write them to blank cards so they could get the special things without paying for and storing all the big bits of plastic.
The blank cards need to be a specific size and the most common ones you can buy on ebay or the like are small stickers which typically cost around £5 for 10 - example listinghttps://www.ebay.co.uk/itm/10-38mm-Whit ... SwB4NWuMFL
Reddit thread on how to make your own Amiibo'shttps://www.reddit.com/r/Amiibomb/comme ... wn_amiibo/
And the reddit community on this is here : https://www.reddit.com/r/Amiibomb
When Breath of the Wild came out a lot of people made their own cards with artwork for the game on them to use and these sold on places like Etsy and Ebay for very little more than the cost of the materials to make them although with Animal Crossing it seems people are charging quite a bit more
A few examples of what people are doing with these for Animal Crossing :https://www.reddit.com/r/Amiibomb/comme ... the_cards/https://www.reddit.com/r/Amiibomb/comme ... cards_pvc/https://www.reddit.com/r/Amiibomb/comme ... ibo_coins/
I was interested in this a while ago and also wanted a cheap second phone for Pokemon so bought this one :https://www.geekbuying.com/item/product-374424/
and it was about £100 all in (on offer i assume) and nowadays its slow and has plenty of marks on it but its still my spare pokemon phone :-)
At the time the program you used to write them (Tagmo) was only supported on a limited number of phones and chipsets but that was a listed compatible one so i grabbed it.
I've not looked at this stuff in quite a while but will have a play around with it to see if i can still get it going and how complex it all is now.