A Lego payload cart for the 72 hr jam, along with a checkpoint. Made in Lego Digital Designer. The bomb can be taken off the cart, and the dome of the bomb can be removed to reveal an alternate checkpoint piece for when you capture it.
As far as I can tell that dome piece doesn't actually come in any sort of opaque blue, so you'd have to make a RED cart if you used real pieces.
I made a bonus mini version as well, along with an Engie and a sentry.