This got me into the hobby in 1961. My dad bought me one for Christmas. Little did I realise this was to start me on a lifelong hobby and career in mobile radio.
It had spring contacts on a baseboard and allowed a myriad of circuits to be built without soldering. As I recall, I was DXing on Medium Wave that Christmas. One project was a small transmitter that got me across the house on medium wave. It used the crystal earpiece as a microphone.
See https://www.radiomuseum.org/r/heath_electronic_workshop_19_jk.html
I cannot recall where the photo came from, but if I have caused copyright issues please tell me so this can be corrected. I have no wish to cause any problems.