Yeah his site isn't currently the clearest for that.

Here's a direct link to his build instructions [1] and I've made a temporary by-item BOM [2] while he improves things.

PETG is great, ASA and ABS might be better if you have the capacity.

     [1] https://la3emedim.fr/assets/SMALLEST%20-%20README.pdf  
     [2] https://docs.google.com/spreadsheets/d/1XXZB4jRtvtlDIqlR69C0FRri8x8lZDpxO6ZGnSp3L2Y/view