My TRON themed ball machine. Made summer-fall 2012. Designed to be viewed under a blacklight, hence the two videos.

Step 1: Flat Spiral

I haven't ever seen a flat spiral made from track connectors, so I thought I'd post mine.
Pictures 3-6 are from my new ball machine.

Step 2: Alternate Elliptica Rails

Since I don't have many gold connectors, I made alternate rails for the IAC's elliptica that use green track connectors.
IAC's instructable is here: https://www.instructables.com/id/Knex-ball-machine-element-The-Elliptica/

The rails are a little closer together, so the axle needs to be adjusted as well.
The top half attaches to the blue connectors at either end.

Step 3: Micro Roller Coaster Track

Not too hard. Similar to KneXtreme's path, but connects the rails together with micro pieces. The easiest way is to use short yellow rods with a yellow connector on each end. Attatches to the tower using transitional pieces, similar to a mini roller coaster.Easy too build, doesn't sag much, rolls very smoothly. Turns are easy, drops are near impossible (unless you have the curve pieces).
KneXtreme's track can be found here: https://www.instructables.com/id/KneXtremes-Guide-to-Ball-Machine-Elements/step13/Mini-Roller-Coaster-Track/

Step 4: Roller Coaster Bridge

A simple way to use three railed roller coaster track to bridge gaps. This technique minimizes sagging. Use the dark orange rods for the bottom rails, and put the track connector in the separated spot so that it cannot slide. Put a red rod through the center, and a blue spacer on each end. This prevents the rod from sliding through the connectors, which is what would cause the track to bend. Middle rail on the bottom is optional.