Question: I was wondering on how I'm able to join all of these separate objects into one, and be able to apply one material using a UV texture with a color grid? is there any tutorials on youtube? Im only used to maya UV texturing. thanks.

Answer: 
To join the objects, select them and then press CTRL + J.
but I imagine you only need a color grid material for all the objects in the scene and not really having them joined.

the easiest and fastest way to achieve this requires using and external addon.
<http://renderhjs.net/textools/blender/>

Once you have the addon installed you can just select all the objects in the scene (no need to join them) and assuming you already UV unwrap them, then in the UV window under the **TexTools** tab just press **Checker Map**. if you keep pressing **Checker Map** it will scroll between various grids

[![enter image description here](https://i.stack.imgur.com/KsM40.gif)](https://i.stack.imgur.com/KsM40.gif)
In order to accomplish this, the easiest way is through the 'Texture Atlas' add-on.

1. Open user preferences Ctrl + Alt + U. Go to 'Addons' tab on the top bar. Search for 'Texture Atlas' and check the box to enable it.

[![enter image description here](https://i.stack.imgur.com/Q36eF.png)](https://i.stack.imgur.com/Q36eF.png)

2. Once you have it enabled you should see a section for Texture Atlas under render settings tab of the properties panel. Create a new texture atlas (in the image below its named 'cannon'), select all the objects that you want to make a UV texture for and click 'Add selected'

[![enter image description here](https://i.stack.imgur.com/p7UGc.png)](https://i.stack.imgur.com/p7UGc.png)

3. Next, click on either 'Auto unwrap' (to let the program create the UV layout) or 'StartManualUnwrap' (to do it yourself manually).
4. Once the unwrapping is done, don't forget to click 'FinishManualUnwrap'. When you do this, the objects will still be separate but share the same UV layout.
5. If you want all the objects to share the same material, you can select all of them and press Ctrl + L. You will get an option to link materials When you click on materials, all the objects will have the same material of the last selected object (shown in light orange)