Before V8, there was V7 — the first version to replace the relay with a DPDT switch. Here is a complete walkthrough video.

VIDEO
What the video covers:

Overview and key specifications
Parts list before assembly
KiCad PCB design walkthrough
3-step calibration procedure
Measurement examples (inductance and capacitance)
Diagnostic screen (DIAG mode)

V7 established the core concept of manual calibration with a DPDT switch. V8 then refined the sketch — reducing flash usage from 95% down to 80% and restructuring the code for readability.
If you are considering building your own, V8 is the recommended starting point:
👉 https://github.com/Nobcha/ARD_LCM_MANUAL