I've been meaning to find out how much conductive silver paste is actually needed for a PCB. I used an old gerber file for a #T^2 Tiles [gd0095] board I never got made. Long story short, Fusion 360 kept crashing when using the svg (converted to dxf), so I just went with a simplified dxf.
Looking across the internet, it seems that the going rate is £4/ml and up (incl 20% tax).
Then, even with this first-seen-in-industry, as-non-toxic-as-PLA-in-liquid-form resin I found out about yesterday that costs £78 after tax for 500ml, I'm only looking at £1.0998 in material. I'd like to believe that some high temp resin or "digital soldermask" resin would cost less than this.
Assuming the conductive paste is £4.50/ml, the final price is £1.10 + £1.62 = £2.72 for a 122x42mm (5124mm^2) board, which is actually in my league budget. The square area is 51% the size of the 100x100mm boards for $2 at JLCPCB. I had a second revision, 3993mm^2 board fabricated (which was 110mm on the long side so couldn't get the offer), and the minimum order quantity (MOQ) of 5 cost £8.70 with ultraslow shipping, coming in at £1.74/pcb. Extrapolating the above, a print of this size would cost £2.12 and should arrive wayyyyyy faster than 4 weeks. Likely even faster than next day delivery.
These conductive paste's required quanities and prices per ml mean that it's also not favourable to use the L^3 method. I imaginee that the lowest end minimum fill level for even a silicone-tube-only (no tank, but collector pump straight to application pump) cartridge would be >15ml.