As several new members of this forum have asked me privately tips for building my LRL want to do a little summary about its construction and calibration.
The quartz and TR1 constitute the internal oscillator, TR2 is the mixer to which the 8Mhz signal arrives along with the "phenomenon" picked up by the antenna. TR2, TR3 and TR4 are the high gain amplifier, TR5 takes the signal (rectified by diodes) with high impedance and  on the emitter there is the signal with low impedance. R15, R16, C17 and C18 are a low pass filter that cancels signal residues at 8 Mhz. I repost schematic and PCB. It's better to use a double face PCB, on one side we sold the components and the other side there is the shield
connected to ground, to avoid self oscillations. It's preferable to use transistors type BC...C because the high beta (gain), I use BC183C because I have a lot but work well also BC549C, BC109C, BC239C and others. All sensor stage is powered by 12V stabilized. For the first test do not connect quartz then look at out point, the DC voltage must be 0V. If not the stage is self oscillating then you must decrease the gain by changing C13 and C14 (from 560pF to 470pF or less) until there are no more oscillations.                                 Now connect quartz and measure out voltage, if the voltage is yet 0 you have to control the emitter of TR1, if the oscillator is ok it must be a 8Mhz signal of few volts peak to peak, otherwise change C1, for example from 330pf to 470pF or more. Signal out is better in the range 5-6V, if it is more then 6V you have to decrease C2,C3 and C4, sometimes it's sufficient the parasitic capacitance of PCB (removing C2, C3 and C4) or you can use instead of C2-C3-C4 two wires of about 6 cm twisted between them. If signal out is less than 5V you have to increase c2-C3-C4, for example  if you use only C2 you have 1pF, if you use only c3-C4 connected in series you have 0.5 pF and so. To test if everything is ok touch the antenna and the out must decrease (100 - 200 mV or more). The target is signaled by an increase of the output voltage. 
I want to add that the sensor stage is very sensitive and must maintain his development away from electromagnetic sources of interference. The same measuring instruments affect the function. I recommend using the oscilloscope only to control the operation of the oscillator, but not use it to measure the amplitude of the signal on the collector of TR3 and TR4, as this will radically change the output signal. The only useful measure without "side effects" it's the DC voltage at output of sensor stage. A useful indicator of good functioning is that the DC output is stable, but if there is superimposed an oscillation of a few hertz or more this means that there is a self-oscillation. I want to mention in passing that this LRL, in the first version, was a RF sniffer that self oscillated, but the output was stable and, quite by accident, I realized that functioned as LRL.
L1/C10 is pass band filter, if you remove L1/C10 or change values (more than 3 turns or less than 2 turns) the lrl don't work. The 8Mhz signal is somehow modulated by the "phenomenon" and this may vary from 3 to 10 Mhz. I can even add that frequencies of about 60 kHz do not work.
Much as regards the box, I always use plastic (easier for me to work) but I would think the wood is suitable, since there is not involved static electricity.