Here is my armor set I designed for my original character. I made the armor to be attached using velcro and or straps and eva foam as a support material.
The helmet I just attached the visor using hot glue since my magnet plan didn't work out for me on the actual build.
Chest armor I added strips of eva foam to form a cross section then glued velco to that to attach on the chest.
Shoulder armor I used eva foam with velcro to also attach to the shoulders.
Hand armor I used velcro for the back of the hand then hot glued the finger tips and base to gloves.
Forearm and shin armor I used straps with clips.
Tasset armor I made eva foam loops to feed a belt through and that were hot glued to the tasset belt armor and codpiece. Then I used strips of eva foam hot glued to the tasset belt for the tasset side plates to hang down from.
Bolt detail I printed separate to adorn the armor with. In the case of mine I printed 4 with 2 on each shoulder.
This is just how I decided to put this armor together to give you an idea of my thought process. Also available on Thingiverse.