Objective:  Use laser-induced photopolymerization (also known as stereolithography) to fabricate a plastic key that can open a lock as specified by the competition director. The competitors need to use the equipment and materials given by the organizer to assemble a system, and use the system to fabricate the key.

Subteam Size Per Entry:  2
Maximum Entries Per Team:  3

A. We will provide:

  1. A blue laser pointer (https://www.ebay.com/itm/20pcs-10Miles-405nm-Laser-Pointer-Pen-1MW-Blue-Visible-Beam-Light-Star-Caps-USA-/311741854361) Beam shape is elliptical (6mm x 4mm). Laser power is 1mW. Wavelength 405nm. Powered by two AAA battery (provided).
  2. 1 – manual 3-axis stage. xy travel range: 6.5mm, z travel range 10mm, accuracy 0.03mm. Dimension of top mounting plate 60mmx60 mm
  3. Photopolymer (also called resin, various color and strengths, similar to https://formlabs.com/materials/ )
  4. Optics (lenses, mirrors, etc) and hardware (mirror mount, etc.)
    1. 1 – 50 mm focal length lens convex lens
    2. A microscope objective (NA 0.25)
    3. 1 – Flat front silvered mirror

 B. Teams can provide:

  1. Reservoir for Photopolymer, with a size no larger than 8 cm x 8 cm x 8 cm.
  2. Eye protection glasses
  3. Mounts
  4. Other materials as they deem necessary, as long as it fits inside a 30cm x 30cm x 30cm box.

C. Details:

  1. Teams will design a key capable of opening a warded lock (see resources). The key will be printed on site, during the competition.
  2. Teams will be given the warded lock design at the start of the on-site assembly. Teams will be provided with blueprints of the lock and have the opportunity to examine the lock.  Teams must be able to adapt their system to print a key that is capable of opening the warded lock.
  3. Teams will be given a target time, of up to 40 minutes, in which the key must be printed.
  4. The lights in the room will be off during the printing process and there will be a red LED light bulb on during the printing process.
  5. The team will assemble the printer onsite using any material they wish to bring with them to the competition. All parts used in the on-site assembly of the printer must fit within the space of a 30cm x 30cm x 30cm box.
  6. Teams will have 60 minutes to assemble the printer.
  7. Teams will print their key after the printer is assembled. After the key is printed, no further modification can be made to the key.  This includes using a knife or file or smooth edges.
  8. Teams will use the printed key to then test opening the warded lock.
  9. Teams will have 3 trials to open the lock. If the lock does not open in the first trial, teams will have 5 minutes to make minor modifications to the lock (such as shaving off any excess material which may be caught in the lock mechanism).  Teams may not make major alternations such as changing the shape of a key tooth.

D. Scoring:

The following aspects will be used in the determination of the ranking of teams.  Higher Scores are given more favorable rank.  Higher Score Wins.

Scoring Rubric

[table id=3 /]


Key Turns = (4 – Trial Number)x(1000)

Key Opens Lock = (4 – Trial Number)x(5000)

Trials = 3000/(Trial Number to Open Lock)

Material Waste = (Starting Mass of Photopolymer provided) – (Mass of Key)

Overall score = (Key Turns) + (Key Opens Lock) + (Mass of Key [negative]) + (Material Waste [negative]) + (Target Time)

Negative Scores are possible.