It's quite complicated to achieve.
I used cyanolyte glue to glue the different elements.
1) To fix the card pico module 75 I glued the card holder piece (the big one between the 2 electronic cards above the power button and the small one above the mico usb to solidify)
2) the power button is made of 3 pieces, the "button power addition" can be filed to adjust the contact with the button on the electronic card.
3) for the + and - buttons are glued to the "+ and - rod" which must be adjusted in order to have a good contact with the buttons of the card.
4) + and - support is made to fix the "+ and minus" socket it fits and is just below the electronic board. For it to be fixed I pasted it to the button - (the one below).
Pause code for change filament color : (first line, 12.9 mm and 17.9 mm for the middle band)
G1 X0 Y5
G1 X0 Y5
Do not hesitate to ask questions if necessary because it is not very easy to realize
link of non-printable parts:
https://www.fasttech.com/products/3828300 (18650 case)
https://www.fasttech.com/products/5573600 (istick pico 75 module)
https://www.fasttech.com/products/3441408 (510 pin)