Classic computer replicas, such as the PDP-8, Altair 8800, and KIM-1, are popular among enthusiasts who enjoy assembling and using these nostalgic machines. These replicas often utilize modern technology, like emulation and kits, to recreate the experience of working with historical computers. Enthusiasts find joy in both the assembly process and the hands-on interaction with these vintage systems, fostering a deeper appreciation for computing history.