Just like the title says.
I’m trying to make a game lobby around a post-apocalyptic theme, so I’m trying to find ways to create moss effects, grass, vines, etc. without taking too much time on details like that.
I was planning on making just a couple different assets of grass, for example, and just resizing/copy-pasting/rotating it around, but I don’t have any specific ideas on hand to create such assets without spending hours on them
You could make a set of, say, leaves for trees, and a set of tree trunks and script a system which randomises them. That way you can get more natural looking trees - I’m sure you could use the same system for other foliage, too.
That sounds neat, but I’m primarily a builder and a script like that would help if I’m trying to make a bunch of grass over a wide area of terrain, but I’m just looking to make small clutter and put it in very specific areas of the build (such as specific parts of the sidewalk, on the sides of some buildings, on destroyed vehicles, etc).
Oh, right. Well, I can’t really help you because you aren’t a scripter, but you could get a scripter to make a system which just replaces parts you set with moss and foliage - like you set a part of the sidewalk to have moss on it, and the script would replace that part with moss. Eh, I don’t know. There isn’t a really easy way without scripting, I’m afraid. Sorry I can’t help more.
One of the easiest ways - while still keeping your game running smooth - is to make your meshparts as versatile as possible. Use the same mesh for moss, bushes, and trees, just stretched in different ways.
Depending on the game style, a textured meshpart could work too, but textures can get really heavy especially when you could just use Grass material so keep that in mind too.
And remember to use Box CollisionFidelity, and CanCollide False so collisions aren’t weird. 
Edit:
Another way is dependent on your specific style (for most cases refer to above), but I made a map that had a “blocky” style to everything which reflected on the trees/bushes as well.
I have an idea. Build/model a random amount of leaves, flowers, branches and other parts of the plant and then use those parts in random re-arrangements. It would help to create a random yet unique look to all your plants. 
I don’t see a problem of you spending hours on making those assets. If you really want a better lobby, try to make a few assets, such as trees (e.g. pine trees, normal trees etc.) and small plants or whatever else you need. If you don’t want them to look ALL THE SAME, you can try rotating and scaling them differently from each other. I believe it will take you more to find a scripter to script that for you, than making a few assets yourself.
