The Thunderbolt is a printable AR-308 lower that, unlike other printable lowers, is built using several individual printed parts which bolt together. This lower conforms to DPMS specification and as such is compatible with commonly available DPMS parts, as well as the AR-15 parts which are interchangeable with DPMS AR-308 designs. Due to the printable lower’s design, any individual piece that wears out or fails can be reprinted without having to reprint the entire lower.

As the name implies, the Thunderbolt is the “big brother” of the Firebolt and uses many of the same design principles. Like the Firebolt, the Thunderbolt utilizes a U-bolt to further strengthen the buffer tower. However, unlike the Firebolt, which was designed to support multiple calibers, the Thunderbolt is solely specialized for use with the mighty .308 round.

At time of writing this is one of the few printable lowers supporting a full-sized rifle round, and its extensive documentation makes this a fine project for any gun printer.