3d in construct IS possible but it is "difficult"
and really it is only simulated 3d (but not really)
the 3d object in construct allows for X Y & Z positioning as well as rotation however it does not support animations
also you cant really use ANY behaviors ( more specifically related to movement)
you have to program EVERYTHING and i mean everything from scratch
by default it allows easy forward/ backward movement in a "3D" world (up and down too)
but what is the fun in going forward and backward? not much!
the hard part is coding how to turn around
basically, in construct, the camera DOES NOT MOVE (well it does scroll in 2d but that is irrelevant)
in 3d it will ALWAYS FACE THE SAME SPOT! in 3d games the camera usually faces the player right?
therefore THE PLAYER CAN NOT MOVE EITHER!
this means the ENTIRE world has to move instead!
this makes things a lot more complicated mathematically
back to what i was saying about turning
the whole world rotates around a focal point(usually the player)
so when the user hits left everything must rotate right and vice versa
when it comes to moving the camera it becomes a beast of a different nature
then you need to set a new focal point and or viewing angle
biasicly, any type of 3d without the 3d object is impossible and that object does not have enough options to make a good game
for example you cant animate the models
nothing like having the player move but the character does not walk!
due to the release of construct 2, it would be better to wait til the developers port the 3d object
and add some of the "missing" features
this will take some time
but as a definitive answer to your question, yes! but this breaks a lot of construct's features due to how you have to simulate things
also as a side note, there are other ways (easier) ways to simulate it (less math) but takes like at least 3 to 4 the cpu
as for level design... it is near impossible to do in construct's UI
I'll have to setup a custom program to design them however there are problems with that!
the 3d object would have to let you change the model/set the model at runtime which is not currently supported
while the cap file is still in early development, i will be glad to help with and share my knowledge for 3d apps