In Spring 2016, construction of the HATPI building at Las Campanas Observatory was nearly completed. The concrete pier for the equatorial mount had been poured and aligned. Plans were in place to install interior electrical components, power, HVAC, and internet connectivity. The facility consisted of two parts: a large instrument bay with a roll-off roof to house the HATPI instrument and allow for maintenance, and a shed containing a server room with computers to operate the telescope mount, acquire and analyze image frames, and store data. The shed also featured a small "observer's lounge" for maintenance personnel. Although HATPI was intended to operate autonomously, having on-site facilities for emergencies was considered useful.

In Summer 2016, the engineering design of the HATPI mount and instrument holder units was finalized. The plan was to use 63 lenses attached to low-profile back-illuminated CCD cameras, controlled by focus and fine-pointing actuators. The mount was designed as a stepped pyramid to allow easy access for maintenance personnel from above and below, coupled with a heavy-duty equatorial drive capable of handling several tons of moving instrument weight.

By Winter 2017, the HATPI mount was completed and ready for integration with the rest of the instrument.

In early Summer 2017, the first stage of mount installation and electronics setup was completed, and integration of cameras and lenses into the instrument began. More installation trips were planned throughout the summer and fall as cameras and lenses continued to be delivered in batches.

In Winter 2018, on-sky testing of HATPI began. The full instrument was integrated, and IHUs were being populated with lenses and cameras as they rolled off the assembly lines. The roof and mount operations had been automated, enabling HATPI to observe autonomously.