I’d try maybe making a simple mesh in blender, or, try using some from the toolbox,
but i think the most easy solution and best one would be to simply reduce part count.
if you’re making multiple tycoons, and multiple droppers, with multiple things dropped, the part count in the game rises like you’ve never seen before.
though, you dont have to make it just one part, from what you’ve said the current ones are very detailed.
try doing a simple but eye-pleasing way. and if it doesnt fit with the map and rest of the game, well heck, change the aesthetic! 
hope i could help.