Just thought I'd share a little tip for mounting PCBs. Some PCBs have holes intended for screws or bolts, but some don't. In this case what do you do? Well, you could risk drilling your own holes, if it's a single layer PCB & you hold it up to a strong light so you can check for places where it's safe to drill. Another alternative is using a double sided sticky pad [or sticky backed velcro]. But if you're like me & not fond of using adhesive stuff to permanently stick something to bare electronics then you may be wondering if there's another alternative. There is another way. You'll need: Drill with 3mm bit suitable for whatever material your mounting the PCB to M3 bolts M3 tapped spacers, like these masking tape black marker Arctic Silver [or similar] 1. 1st you need to mark where to drill the holes. Figure out where your going to put the PCB, then put some masking tape on the surface you're going to be drilling into. 2. Use the marker to black-out the masking tape, especially where you estimate the holes are going to go. [makes it easier to see the arctic silver - just trust me, you'll understand in a minute ] 3. Put a tiny blob of the arctic silver on the end of a bolt [not the end with the screw head on]. 4. With 1 hand, hold the PCB just above the surface it's to be mounted on, in the position you want it to go. With the other hand hold the bolt with the arctic silver on the end against side of the PCB, with the AS'd end pointing at the surface to be drilled. Slide the bolt down until it touches the blackened masking tape & makes a nice little silver blobby circle. 5. Now you know where to drill your 1st hole. If you're drilling into metal it might be a good idea to use a hole punch in the middle of the silver blob. 6. Drill 1st hole. 7. Put bolt through from back of mounting surface & screw on M3 threaded spacer [all the way down, so it's nice & tight]. 8. Repeat from Step 3. I recommend the 2nd bolt be the 1 at the other end of the same side you did the 1st 1. 9. When you've got all 4 bolts [or more if it's a bigger PCB] in place your PCB should fit snugly between the bolts. To make sure it can't fall out or lift up [for example when unplugging a cable from the PCB], simply screw another spacer onto each bolt until it's down tight against the PCB. Hopefully this may be of use to someone, just thought I'd share this little tip.