@asvjerry The DIY Ribbon Speakers were a follow on to an investigation into building a Stax Type of ES Headphone, from recollection there is a Part that can be purchased very cheaply that enables the Stax ES Type to be produced.
It become apparent, both the ESH and RH DESIGNS, could have all parts required prior to assembly purchased for approx’ £100.
If the most desirable aesthetic is wanted, the price will inevitably increase.
The owner of the Stax ES Headphone was absolutely lost for words, when the discovery was made that the Ribbon Type was bettering their Headphones at approx’ a twentieth of the cost.
The same builder of the Headphones is also the Builder of the other devices I mentioned earlier using the Korg Nutube.