Hello,
I want to ask if it’s possible to design an invoice template?
Do I need liquid language developer?
Yes. I’ve developed mine through a try and adjust process starting with my skills in html and PHP which are very similar.
Davide with your skills can you calculate total of qtuy column and share an example theme, i am strugling to do that
I’ve never tried. I’ve changed the aspect of the theme and move some custom fields in specific area. I had in mind to have a subtotal fixing the number of lines in a custom field (something very similar to your need) but I’ve never had time to develop it…
thank you however for your answer David
the develpers have added a way for calculating custom fields in guides may be they will add this shortly
i just have to wait 
Can you share with us?