Hello,
The coils look like they were made by Gambrell (
http://www.valve-radio.co.uk/coils/g...-plug-in-coil/) which came out circa 1923.
Gambrell did produce a similar wavemeter in 1923
https://www.radiomuseum.org/r/gambrell_wavemeter_a.html and here is another similar one by Bower-Lowe
https://www.radiomuseum.org/r/bowyer...ave_meter.html
You can see the marking out lines on the underside of the ebonite sheet which suggests that it might be "homemade" as you might have expected a manufacturer to use a template etc for drilling.
Yours, Richard