Mine worked first time. I built one previously on stripboard but couldn't resist the prospect of building another with a more professional board layout - the quality is superb. Luckily I had most of the parts including a salvaged 2N3819 and BC109 that had been lurking in the spares box for years. Both worked. like others I found the 680nF cap was too big when it arrived and so I fitted two 330nF in parallel which was a snug fit but OK. For a box I found the following 100mm x 100mm junction box ideal:
https://www.ebay.co.uk/itm/Plastic-J...-/352876701871 Even the holes in the minimod board line up with the box mounting holes and plenty of room left for the battery. I didn't bother to fit the LED so I will have to mark the on-off position of the mini-toggle switch. Cheers, Jerry