As I started this Thread and got some very helpful advice I think I should bring you up to date.
The idea for getting the PCB made was to make it easier to attach an Attiny 1634 to an nRF24. As you can see the way I have been doing it is rather tedious but does make for a very small package.
What I was thinking of getting made is a very small PCB like this (just one side to give the idea)
So the Attiny could be fixed on one side and then the board could be dropped over the pins on the nRF24 with the Attiny on the underside. Then all the contacts that need to be accessible could be on the visible side of the board.
I had nearly finalized the design when it occurred to me to consider again the possibility of using an ESP8266-12 0r -07 as an alternative to the nRF24 and Attiny. Previously I had been put off by the need to deal with all the WiFi "infrastructure" and the possibility of needing a router or Access Point.
When I took the time to consider the ESP8266 properly a few days ago I discovered the ESP-NOW mode of usage which allows you to use them in a peer-to-peer arrangement just like an nRF24.
And, making a working ESP8266 by soldering on 2 rows of header pins and 4 x 10k resistors is far far simpler (and cheaper) than using an nRF24 and an Attiny 1634 even if I had the PCB so I have (for now anyway) given up the idea of getting PCBs made.
I have written about using the ESP-NOW protocol here.
...R