Abstract: An apparatus for forming one or more blocks from carbon dioxide particle is configured to allow changing between precise thicknesses with very little downtime, utilizing both weight based and volumetric dosing. A spacer supports the lower ejection piston during block forming, with a shuttle discharging particles into the forming chamber while simultaneously pushing one or more previously formed blocks on to a conveyor. In one embodiment, the shuttle dosing cavity has a volume that is greater than the volume of the forming chamber volume, which allows more pellets, volumetrically, to be dosed into the dosing cavity than the volume of the forming cavity.