Help with Coloring and Smoothness

I am in the process of experimenting with various methods of producing mycelium tiles. Based on my initial tests of mixing spawn and (cardboard + sawdust) substrate into a mold the result is a pure white bumpy tile. I am looking to make changes to the process to achieve two changes.

1.)reduction of rough/bumpy texture
2.)Increase brown coloring

The picture below contains examples of what I am hopefully explaining. The left is what I currently have, White and rough texture. The right is what I am looking to recreate, smooth and brown coloration.

(Sorry for the not high quality picture)

My thoughts on how I may achieve these traits are below, but welcome any thoughts or suggestion.

1.Texture - can reduce rough texture by using smaller and fine substrate. Utilize blended cardboard and saw dust to create a more dense substrate and then apply weight to pack tightly. Attempt to grow with weight/pressure on top of mold? Periodically apply pressure to mold to obtain smoother finish?

2.) Color - the research I have done related to the image above on the right says that the method of colorization is a result of temperature used during growth. I would assume this would be the introduction of heat to the growing mycelium to create stress and in turn browning? Not sure on when to introduce the heat, the best temperature, or length of exposure?

Hello, you can also get yellow spots on your mycelium by letting water pool on the surface. Usually people want to avoid this for aesthetic reasons, but if you like it then try letting a few drops of water hang around during growth and drying! The drying has to be done after the mycelium has grown to the extent you wish. I would first grow the panel in a mould for a few days, then take it out of the mould for a few days until a fuzzy white layer of mycelium forms on the top, and then whenever you want to stop the growth, put it in the dryer. A higher drying temperature should brown the surface. Hope this helps!