Reflection ⭐


Art installation “Reflection” is a result of the Signal Calling open challenge, backed in 2019 by PrusaLab. The winning duo, architects Adam Cigler and Petr Vacek were given full access to PrusaLab including all equipment and help from the staff. Six months of hard work later, the installation had its debut during the Signal Festival itself.

“Reflection” consists of dozens of independently moving mirrors. Each mirror is actuated by two servo motors and could tilt in any direction. Each mirror, its motors and a 3D printed supporting frame together form a movable module. Five such modules are attached to CNC-cut plywood panel and connected to a common servo shield, forming an independent cluster, which is controlled by a Raspberry Pi minicomputer. The whole installation includes 18 such clusters, controlled by six interconnected Raspberry Pis.

There is a tailor-made software which not only controls the mirrors but also synchronizes the movement with lights and music. Apart from the site-specific animations compiled in a 3D environment, the mirror wall could be animated with remote-controlled accelerometers. It’s a sophisticated technical system, mirror reflections are continuously morphing and changing. This hypnotic transformation provides a unique audiovisual experience.

Reflection stats

months of work
visitors during the Signal Festival


Reflection in action

Under construction


Trailer from the construction process

Trailer from the St. Agnes monastery

Reflection in time

Right from the start, the modules were designed to be 3D printed.


This is the first version. Originally, the circular holding frame was printed from a bronze fill filament.


Later we used grey PLA instead, focusing more on the durability of the whole module.


Thanks to parametric 3D modeling, it was easy to change the circular frames to hexagonal, better matching their shape with the mirrors.


“Parametric” means that a 3D model exists as a script, in which you can easily change one parameter and the rest of the geometry recalculates automatically.


Then we started to print first versions of the construction.


Testing and adjusting the design took several weeks.


A few iterations later we put the first mirror in motion!


However, the first versions were not flawless yet. For example, the actuators were falling out of the construction.


Finally, the 11th version had the actuator system solid enough.


While testing the construction, we realized that for quick assembly, the cluster bottom panel has to fit into the corresponding holes.


We tested the functionality of each 5-module cluster, to find possible errors in the servomotor wiring.


The biggest challenge was to get rid of the mirror fluttering and make the animation smooth. We solved this by optimizing the 3D print parameters and reinforcing the construction with metal fittings.


In half of September, we received a long-awaited servomotor shipment from Taiwan…


…and we could finally start mass-producing the modules!


We couldn’t complete such a large size assembly without help from 16 volunteers. For two weeks, PrusaLab was changed into a dedicated production line.


A static calculation of the steel mainframe dictated a huge maximum load, to prevent the installation from tipping over in a strong wind.


Together we had to use 525 kg of cast iron blocks, formerly serving as counterweights in an industrial lift.


To prevent any nasty surprises, we made a test assembly in our warehouse.


Then we disassembled it again, and off to the St. Agnes monastery!


As we had really bad weather during the assembly, a thorough waterproofing of the construction really paid off.


We tested both animations and sounds before the performance.


The unique experience attracted more than 60 thousand visitors. Thank you!



Adam Cigler & Petr Vacek


electronics, control software 

  • Matěj Suchánek

3D printing

  • Michal Trnečka


  • Dalibor Souček


  • Bob Heida


  • Martin Múčka

production & management

  • Jan Hanzelka (produkce)
  • Ondřej Kašpárek (management)


  • Matyáš Cigler
  • Jonáš Rosůlek

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