Mammoth only supplied a few PCBs of ours as kits.
I fully endorse PedalPartsandKits who do an excellent job drilling the enclosure so it is suited to each and every board while also making sure all the parts are included. PedalPartsandKits take the extra time to individually hand drill each enclosure to be aligned perfectly to suit each and every unique board we carry.
Additionally purchasing parts for me is always done through the likes of Mouser, Digikey, Small Bear and PedalPartsPlus who are all in the USA and have excellent prices. I realize Mouser has a slight “filter learning curve” but it is really pretty easy considering the vast amount of items they carry. Any oddball pedal stuff if not available at Mouser or Digikey can almost always be found at Small Bear and PedalPartsPlus. Mouser now offers a 1st class shipping option as well.