Alcator says:

sonixerik says:
What about an MTC called Less than 90 degrees where you build a track which doesn't go vertical by 90 degrees or more.

i.e., no U-ramps and no loops?

the themes should be in "positive" manner: The track MUST contain this and that. Or: The track MUST have this and that property.

Actually, a theme is a restriction. It can be in possitive or in negative (aka Block bans).

What about a pass under MTC. Build a track which involves driving under a piece of track you've driven on/about to drive on a set number of times.

Seriously?

2 easy

Sonixerik's idea has reminded me of one I had some time ago: How about building a track where we use the 2 levels of some blocks at least n times? Where the blocks that have various drivable levels are the loops, the platform tunnels, to some extent the wallrides and platform blocks, and as a final instance the canyonside road with a huge wall.

What about a Underground MTC? Build a track which is underground, with the exception of the start and finish AND uses every underground block at least once. Furthermore, due to the Canyon and Stadium having multiple entrances, a minimum of 5 blocks can be used when connecting a tunnel exit to another tunnel entrance.

A 9 block challenge map, where you can only use 9 different blocks, including terrain. Blocks that change upon different surfaces are considered the same block. It also includes the Start and Finish pieces and Checkpoints. You can use as many of the 9 blocks you have chosen but only those 9 blocks.

Here's one called one terrain MTC. Build a track which uses only one type of block to race on. For example, if you choose racetrack blocks, you can't use underground blocks, road blocks or platform blocks. If that type of block does not have a start and finish block to it, a transition block can be used to connect a start block and finish block to it. For example, the platform tunnel blocks or underground blocks.

That idea is probably going to receive criticism, and I was gonna say it could easily get repetitive but I suppose that avoiding that indeed would be the challenge.

For July a simple Valley MTC would fit perfectly, no?