Before you start, I want you to read this tutorial all the way before you try it yourself.
Hello everyone. In this post i’ll be showing you how to go from this:
https://streamable.com/h08ykc
To this:
https://streamable.com/b05gzk
What you will need:
Blender,
Roblox Studio
Smooth Terrain textures (Model)
Step 1: Making the terrain without water
First, we’ll make the terrain without the water. Do not make this too big, you have to keep the amount of triangles under 10 000. You’ll see why later.
https://streamable.com/5for2x
Step 2: exporting the terrain
Before you do this step, make sure that there is no other terrain in your Workspace except the part that you want to export. When exporting you can save the file anywhere you want, as long as you can find it back later. In my case, i’ll just put it in my documents.
https://streamable.com/chezse
Step 3: Opening it in Blender
Now, open up blender. I know blender is a fairly complicated program if you’re new to it, so I’ll try to explain everything as best as I can.
Step 3.1: deleting the default cube.
Upon opening blender, You’ll see a cube. You can delete this by clicking on it, then press Shift+X, then enter. You might see some other elements as well. You can delete those too. (As shown in the video):
https://streamable.com/0sa58e
Congrats! You performed your first shortcut in blender! 
Step 4: Importing and scaling down our terrain
Now, that you’ve cleared the workspace in Blender, we can import our terrain and scale it. To Import our terrain, go to the upper left on your screen, press file and then import. Then choose Wavefront (obj.). Locate your terrain file, select it and then press “Import OBJ” make sure you select the .obj version and not the .mtl, otherwise it wont work.
https://streamable.com/58mlfm
Now for the scaling, just select the terrain and press S. Then you can scale it down by moving your mouse. You can also zoom in and out by scrolling your mouse wheel up and down as shown in the clip:
https://streamable.com/r8upne
Step 5: exporting from Blender to Roblox Studio
Now that you have your terrain set up, we’re ready to export it back to Roblox Studio. To export it from blender, just do the same steps as importing. except now we’re saving it as an .fbx file.
https://streamable.com/kzyv3t
Now let’s open it up in Roblox Studio. We’re going to do this using a MeshPart (this is why you have to keep it under 10 000 triangles).
https://streamable.com/92lpda
So now you have your “fake terrain” in Roblox Studio. But it doesn’t look convincing enough. Let’s apply some textures!
Step 6: Textures
Take the model that I put under the list of what you’ll need. We’re going to use the model for our terrain textures. Note that this model doesn’t have ALL terrain textures. Just the most common ones.
First, select the texture that you want for your terrain. Copy the texture URL. Then go to your terrain mesh and insert a texture. Change the Texture of the texture, woah… You get what I mean. Then change the StudsPerTileU and StudsPerTileV to a number you like. They have to be the same, otherwise the texture will get stretched. Lastly duplicate the texure for every face of the mesh. (just watch the clip already lol)
https://streamable.com/a3vd6c
Now you’ve made your first “fake” piece of terrain! Let’s put this in place and then delete the original terrain.
https://streamable.com/ecn1yr
That’s it for the tutorial part. Now lets go over some pros and cons that this method has(there’s more cons than you think)
pros
It looks very clean
lol only pro i can think of
cons
It’s a very tidious process if you have a lot of coastline
it’s hard to match up two parts of “fake” terrain, as seen here:
keep in mind that I’m not really good at this lol. You can hide this transition a little by putting it in a shadow:
Texture borders are slightly visible:
So yeah, it’s up to you to decide. If you’re making a game that’s more focussed on visuals, then I reccomend using it. if you don’t really care all that much, then don’t.
Closing
This is the first time making a tutorial for me. Feedback is much appreciated! Also if you have any questions, feel free to reply to this topic! And lastly, thank you for reading!
Also for those who are curious, here’s the game: https://www.roblox.com/games/6288776869/Terrain-and-water