Little metal tabs
Fold them over on the silver strip of the heating tape. This is harder then it sounds because they want to bend at a different angle. I used the official (not cheap) clamper-doohickey (red handles in the tool section) to clamp it down because the little metal bits that stick up towards each other MUST meet up and merge and do the metal version of face melding with each other. If you don't get the official doohickey then get some other RACHETING doohickey because god-DAMN that requires a lot of pressure to force to happen.
VERY IMPORTANT: Make sure all the little metal spurs (on the inside of those holes) are ON the silver metal strip in the heating tape. If not, potentially MELTEDPLASTICOHNOESTHESHIPPINGCOSTALONE. Didn't happen to me but I was advised of the risks. It is made easier if you have a pair of needle nose pliers to help. But don't think you can use needle nose pliers as a doohickey because they don't pack enough punch.
I clamped the metal clip onto the tape first because that's how I roll. Some people put the wires in first and then attach it to the tape. Figure out how you roll.
OK - Bottom shelf. One set of wires (strip the end with a wire stripper) goes to the plug I purchased as part of the set-up and the other from me standard lamp wire reel.
CLAMP EM SHUT (The official doohickey comes with an M-section that allows you to seal them in). There are no photos of this because this was a massive P.I.T.A.
Should look like this. Set of wires from shelf A goes to shelf B (where you stick in another set of wires to go to shelf C)
Take the aluminum foil off the shelves because the cats won't stop chewing on it.
CLAMP EM SHUT
End up with something like this
Make sure none of the little metal tabs are touching metal (for heavens sake we're working with electricity, don't be an idiot)
Plug the cord into this
Set the temp. Watch it go.
Or in my case, watch the goddamn thing not work because I got a dud. =_=
Plug it into the wall and the wiring works fine, but it needs a thermostat so I'm getting a new one. Ugh.
Once you've confirmed it works use the little plastic shells (if you bought them. Buy them). Fill one up with silicone, place on bottom, put some silicone in the top, snap it on. Wipe hands of sticky silicone. Swear to never touch the damn stuff again.
Let sit till sticky stuff sets. Immediately ignore promise to never touch silicone again. Put aluminium foil under tape and tag the tape to the foil with silicone to keep it from shifting. Promise the cats no treats if you find tinsel in the litter box.
Have husband regret life choices that led to his wife smelling like silicone and being stuck to all the cat hair.