Tag: resin

Sugru – Alternative to Resin Casting

As an alternative to making mould and casting the electronics in resin epoxy is the possibility of the end user using the sugru to form their own enclosure.


The image above shows the sugru formed using the finger squish method.

Users would need ot use thin white sugru above the illuminated LEDs but would be free to form their own shape and add their own colored sugru.

An additional advantage, other than removing the requirement for production of resin casting, is that it is understood from a non legal view, that the end user assembling the final device from the component parts and sugru housing would allow the talisman to be classified as components and not a final consumer electronics device. Because of this, there would be no requirement for the Talisman to undergo the expensive FCC electrical and emission testing standard process.


Final Prototype (in parcel)

The final resin cast talisman prototype was included in the parcel. Each item in the parcel has a descriptive note in each zip lock bag.


The included resin prototype had all components mounted inside clear resin to allow sculpturing the talisman shape. The final unit will be milky opaque and not clear.

The included prototype did not have a PCB included so one of the two nuts was loose and has been weakly glued in place. The final talisman will have the nut on the top side of the PCB and will not fall out because the PCB will hold it firmly in place.

The final device will be either bolted onto a custom personalised wrist strap, or will be worn around the neck as a pendant with a chain attacked to the rear of the talisman.

Power is applied to the device with a magnetic clasp once a week to recharge the device.

Casting using Mold

A casting was prepared using the silicon mold. The casting was solid resin without any internal electronics. The purpose of the casting was to check if the silicon mold would seal correctly and not spill all the resin.   Surprisingly the very irregular silicon mold did not leak!


The Top side shows a nice consistent ability to graduate the speckled texture to the top surface of the talisman. This texture is visible along with a smooth surface finish without bubbles. The talisman is cast upside down so the texture sinks to what will be the top surface. This is useful because the texture material has sunk and does not occlude the glow above the internal LED.


Also any bubbles rise in the inverted mold and therefore problem bubbles appear on the underside of the Talisman. The top side of the talisman is at the bottom of the silicon mold and never has bubbles sinking down there.


The silicon mold was not perfect and a very clear parting line is visible around the talisman. Any blemishes and inperfections will be manually sanded down.


Hopefully a better casting of the silicon mold would result in a less visible casting line. The silicon used in this mold was past it’s expiry date by 6 months and did not flow as well as fresh silicon.

The quantity of white pigment added to this test was hastily added at the last minute and not measured correctly. The resulting intensity of the whiteness is lower that required and this test therefore looks a lot more milky rather than a quartz like white that has been achieved previously.