Creating a 2d rectangle

I'm trying to create a 2d rectangle in Unity that I want to be able to colour with solid random colours and change size/position with.
I can easily change the size/positon, but I'm really struggling with the colour despite being conceptually really simple. How is this done?
So far I've tried:
* Sprite renderer - but the colour doesn't change and I don't have a sprite anyway, it's just a simple rectangle.
* MeshRenderer with a quad mesh - but:
** Set the thickness to 0 and it turns solid black, so it has to at least 0.00001 thick; not sure why (?)
** The colour of the material has all of the fancy shading effects on,
** The Rectangle is always behind the "background" sprite; There doesn't seem to be a "sorting layer" on the MeshRenderer.
Any suggestions?

 

Try the Image component, and change the colour on that to get it to change colours. If you're looking only for an outline, i've seen some shaders/scripts around that do that, can find them for you if needed.

 

Thanks for the suggestion - note that isn't for the UI, so would a Image component be appropriate? It seems to be a UI thing. Doesn't seem to work without being on the Canvas.

 

I think it should still be fine. You can also look at sprite renderer component it does the same thing but might be closer to what you want.

 

I ended up just using a regular 3d cube but with a Z scale of 0.001. It seems it uses the Z axis for ordering over sprites.