diy CO2 laser tube

Hello everyone, i begin with an apologize for my English mistakes since it is not my native language, i am trying to build a CO2 laser tube by myself since the process seems a little too simple and i want to see what it involves. I could not find any good documentation about this process and i would like to ask if anyone else made it. My main questions are:
-can the tube be acrylic ?
-is it pressurized or just the mix of gasses at "room pressure" ?
-the semi reflective mirror is a big question mark, i have not been able to find any info about this one, i know they have different material mirrors, bot no mention about the semi reflective one. What is the deal with this one ?

Hi,
it is much, much cheaper for you to buy a sealed laser tube and a source, unless you want to assemble a laser tube for pleasure.