This should be roughly what was done here, but written in ruby.

first, in your polybar folder

  $ git clone https://github.com/itsmaia/polybar-crypto && cd polybar-crypto
  $ mkdir ~/.config/polybar/crypto && cp ./{crypto-config.rb,main.rb} ~/.config/polybar/crypto

Then, put your API key (CoinMarketCap) and desired coins at crypto-config.rb.

@coins = { :bitcoin => "bitcoin_icon", :dash => "dash_icon" }
@currency = 'USD'
@api_key = 'YOUR KEY HERE'

In your polybar config file:

...
modules-right = crypto memory cpu temperature date
...
[module/crypto]
type = custom/script
interval = 600
exec = ruby ~/.config/polybar/crypto/main.rb

@willHol used the cryptocoins font in his project and i think its pretty neat, you can take a look at that if you want to.

This is licensed under do whatever you want with it.