Arduino project guidance

My name is Avi
I have very basic electronic knowledge but I have idea for some application that I need.
I would like to build a 15 individual push buttons Analog counter . A 15 triple 7 segment display on each individual count based on Arduino. For the triple 7 segments 15 units I need to build PCB board with multiplexer for the all 7 segment. In addition I will have serial LCD display to sum any combination of the counts and massages.
I have Arduino uno
I need 15 triple 7 segments display , not sure yet if common Anode or Cathode
I have 16 push buttons (one will count backwards the last count in case of error)
I need to know if I need Max7219 , and how many to control the all 7 segments displays (15x3 digits)

I did a Arduino uno setup with matrix keyboard and serial lcd display and simple coding and it is working.

Any idea how to upgrade the hardware

Thank you

@Aviouslybar - I have deleted your duplicate post to an old topic