Glow in the Dark Molecules




Introduction: Glow in the Dark Molecules

This project is based on an old Instructable of mine called the Modular Molecular Lamp. Unfortunately, that make is under my old college email that no longer works so I had to make a new account haha

Anyway, I wanted to upgrade the project by removing the need for LED lighting on the inside and just make the whole system glow in the dark.

Also wanted to have more molecular geometries represented since we can now make different special connectors using TinkerCAD's new codeblocks.



  1. 3D Printer
  2. Glow in the Dark PLA
  3. (Optional) Orange PLA (Or any other opaque colored PLA)


  1. 3D Print Flush Cutter
  2. Sanding Sponge
  3. (Optional) UV torch to supercharge Glow in the Dark PLA

Step 1: Molecular Geometries

So, since we'll be making a molecular kit to represent different molecules, we can just briefly talk about molecular geometry.

Molecular Geometry, also know as molecular structure, is the three-dimensional structure or arrangement of atoms in a molecule.

Atoms usually have varying bond lengths and bond angles as shown in the above image. For this Instructable, I've tried to replicate a bunch of these shapes for others to use but there's still more challenging ones to make like in Wikipedia's full table and other literature.

Step 2: Design

For this kit, I decided to stick with the simple line or stick 3D representation of molecular geometries. Essentially, everything, from double bonds to different atoms, will be represented using just 3 main pieces. (Of course there's other ways you could do it)

  1. The atom that acts as a connector and can have different shapes
  2. A straight line piece to connect different atoms
  3. An end pieces for different legs of atoms that have no straight connectors

Step 3: Straight Piece

Codeblocks Link

These are the simplest pieces to make but also the basis of all the other designs in terms of measurements. They are made up of a connector and sleeve.

You simply take 1 cylinder of the size you want then subtract a smaller cylinder from it to make a tube. You also add a shorter cylinder in the middle of the first two to make a sleeve.

Something important to note is that the first two cylinders must have extremely low resolution (you can set this by changing the "Sides" value to 5) while the sleeve cylinder must have a high resolution (Set "Sides" to 64).

This helps ensure a nice fit when you push the straight piece's connecting end into the opening of an atom's leg. It's technically a simple way of making a press fit.


Height: 40mm

Inner Radius: 6mm

Outer Radius: 6.5mm


Sleeve Radius: 8mm

Sleeve Height: 20mm

Step 4: End Piece

CodeBlocks Link

End caps are just like the straight line pieces.

Essentially, just take a straight line piece, cut it in half and stick a hemisphere at the end. Again set the inner cylinders to have extremely low resolution while the outer cylinder has a high resolution.

Step 5: Linear & Bent

Linear Codeblocks Link

Bent Atom Link

So now, we can move on to the atom shapes.

The atoms are just tubes that we can fit different straight and end pieces to. Their outer radius is the same as the Sleeve Radius (8mm), and the inner radius is the same as the outer radius of the connector of a connector (6.5mm).

The Linear atom can be made using TinkerCAD's Codeblocks but I could only make the Bent atom using a tube shape generator from TinkerCAD's regular editor.

Step 6: Tetrahedral

Codeblocks Link

For tetrahedral, I tried to get the bond angles to be 109.5° (assuming all substituents that would surround the central atom would be the same)

Step 7:

Codeblocks Link

For this form of trigonal pyramidal, I just took a tetrahedral piece with it's top leg chopped off.

Step 8: Trigonal Planar

Codeblocks Link

Flat atom with 3 legs, 120° between bonds.

Step 9: Trigonal Bipyramidal

Codeblocks Link

Trigonal Planar with an upper and lower leg.

Step 10: Octahedral

Codeblocks Link

Trigonal bipyramidal but with 4 atoms around the center instead of 3.

Step 11: Square Planar

Codeblocks Link

Octahedral but with no upper and lower leg

Step 12: Square Pyramidal

Codeblocks Link

Octahedral with only 1 leg

Step 13: T-shape

Codeblocks Link

Just a regular T

Step 14: Stand

Codeblocks Link

And Lastly, a simple stand. Molecular structures seem okay with just being hang on a wall or displayed on a table, but a stand provides an extra level of fancy if you need it.

Step 15: Printing

I made all the parts small so that you could print many of them at once. Just make sure to use your 3D print flush cutters and sanding sponge to clean up the prints once they are done cause they do have a few rough edges.

Print all pieces with supports and build plate adhesion.

Additionally, when printing with glow in the Dark PLA, please make sure to change your nozzle and printer settings as needed to avoid problems and unnecessary wear to your parts.

This link gives a good run down from a Prusa Forum post

Step 16: Done

In my photo's I stuck with tetrahedral atoms cause I wanted to represent hydrocarbons, but there's plenty more atomic shapes and molecular structures you can explore.

Have fun :)

Be the First to Share


    • For the Home Contest

      For the Home Contest
    • Make It Bridge

      Make It Bridge
    • Game Design: Student Design Challenge

      Game Design: Student Design Challenge



    Question 9 days ago

    Can you please let me know where in the UK I can purchase the luminous PLA that you used in this instructable? I. Would love to make some of these shapes.