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How to: Apply the finish to your device

Step 1: Sanding

This is the most time consuming step. You will want to start with the lowest grit you have (120 grit is good).  You want to sand every bit of the cage. The ony exception being the area which attaches the cage to the ring. The reason you don't want to sand the connection between the cage and ring is that the 3D print file has been optimised to work straight off the printer; sanding may cause the connection to fail.


The more effort you take with 120 grit the easier it is later. It's better to spend more time with 120 grit now. 

KB3D TIP- use an electric handheld sander with low grit (80-120). This will speed up the smoothing of the very rough edges where the supports were.

You will be finished with the grit 120 when the cage/ring feels almost like velvet - it's not rough, but it's certainly not smooth either. The important thing is that there is a consistancey across the whole cage - no points that you rub and think "ooh, that was a rough spot".  At this step move onto the next grit. Try and keep each increment as small as possible and try not to skip any grit sand paper.  Repeat the process with each grit. At 400 grit the cage should start to feel smooth. The final grit you stop at depends on the next step. If you are planning on coating your cage, then you can stop at 600-800 grit. If you are planning not to treat the cage with any sort of coating, then I would go as high as you are willing to go. The higher the grit you go too, the smoother it gets, the fewer gaps fort bacteria to settle in. A non-coated cage is fine for short lockups for beginners.  Just make sure you regularly wash yourself and the cage with warm, soapy water.


Step 2: Coating

After your cage is a beautifully smooth 600+ grit, it's now time to coat. There are two options which KB3D has tested:

  1. An acrylic spray

  2. An epoxy resin.

Each one has their pros and cons so it's worth comparing the two below to find out which suits you.


Acrylic Spray:

How to apply:

Check the manfucturer's instructions! The below will give you an idea of what that might be like:

  1. Shake the can for 2-3 minutes. The metal ball should be freely mixing. 

  2. In a well ventilated area spray the cage with long gentle movements about 20-30cm away. I would recommend wearing gloves and a mask.

  3. Leave to set. After about 30 minutes it will be fine to touch but the longer you leave it the better.  


For a better finish, after completing the above, do the following:

  1. After 1 hour I would get a very high grit sand paper (1000+) and give the cage and ring a once over.

  2. would then repeat the entire process, spraying the cage to give a second coat.

  3. Leave to cure/set for 24hrs



  • Glossy effect

  • Very smooth

  • Thin Layer - Does not alter the size of the cage

  • Cost effective - If you only have one cage it's cheaper to use this over resin.


  • Requires a ventilated area + aerosol mask + gloves

  • Does not increase the strength of the cage

  • Not cost effective for large number of cages (3+)

  • Thin Layer - If your sanding is not perfect you will notice anything you have missed.

Epoxy Resin:

How to apply:

Check the manfucturer's instructions! The below will give you an idea of what that might be like:

  1. It is recommended to wear gloves

  2. Mix equal volume of resin and hardener and mix for 3 minutes. You have about 45 minutes before the resin starts to set.

  3. With masking tape, cover the cage attachment and the ring attachment. If you get resin on the attachments, they'll no longer fit together!

  4. Apply the resin to the cage and ring, using a foam brush. 

  5. Bubbles will appear from having mixed the resin.  These can be removed by applying heat with a blow torch, hot air gun or the gas burner from your hob.

  6. Leave to set for 3 days.

  7. Allow the resin to set for at least 6 hours.  During which, check to ensure resin isn't pooling in any specific areas. If resin is gathering in areas, simply dab it with foam brush to remove excess resin.

Adding the resin to the Voronoi with small holes could seal the holes, so keep an eye on this.


  • Easy to apply

  • Significantly increases the strength

  • Thicker layer- so it can cover some imperfections in the sanding/printing

  • Cost effective- Only cost effective for many cages. 


  • Bubbles- Bubbles in the resin can be annoying if you have no way to remove them

  • Thicker layer- If this gets on the locking mechanism then the cage will not work. Also it could seal the small holes of the Voronoi cages. Just blow on the area and it will clear the hole. Would require multiple checks

  • Temperature- Some resins have "softening" points about 50C. So prolong use the resin may soften slightly. This is not dangerous.

  • Cost- For one cage this can be expensive.

  • Time- Takes 3 days to fully cure.


Finished Cage

Once the resin or spray has set, you have a finished cage! NOW GET LOCKED!

We would love to see your finished work! So find me on social media, I'd love to share your hard work.  Who knows, maybe we'll reach out to ask if we can use your images on our website.

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