This is a reverse engineered (with permission from Kevan, aka CaptainKev, who invented them) design for the Lex-Lox track attachment system by TraxPert (Kevan). Read more about them and how they work here (old forum thread) and watch the video linked below: https://www.slotforum.com/forums/index.php?showtopic=73146
It is highly recommended that you run test prints of each piece prior to printing a lot of them. Small variations in filament diameter can effect the fit of the pieces.
The spikes, designed for an 8x4mm round magnet (or a bit of steel) to be inserted in the pocket, are meant to be LOOSE in the round holes on the bottom of the track. They should slide in and out easily. If they do not, then reduce your extrusion multiplier and try again. Don't push it all the way in the socket if it's not just falling in, because you may not be able to get it out! You should only need a couple spikes, as they are meant only to locate where you will screw in the buttons.
The buttons, which you will be printing dozens of, should be a snug fit in the track sockets. Use a screw as a handle when you test, so that you can easily remove it once inserted, since you'll need to install the buttons when they are NOT in the track. If they are loose, then increase your extrusion multiplier (EM). If you can't get them into the sockets, then reduce your EM. Once you've nailed the EM for fit, then you can go ahead and print up however many you need for your project.
The tall spike is for Scalextric Sport Digital pieces, such as lane changers, lap counters, and single lane pieces, which are all about 2mm taller than standard Sport pieces.