Fibergalssing Sub box

Quick questions for you guys out there. I am new to the fiberglass scene but very interested in trying. My question is, I am going to make a sub box and of course fiberglass it. Now I have seen some people lay the fiberglass on the inside of the box and outside as well. Now will it make a difference which method I choose? And what is the best cloth material to lay over the box for the prep of fiberglassing? Thanks in advance!

are you just covering a mdf box?

I have tried a few kinds of cloth, I found that thicker material will warp less during the curing process,   I have had good luck with the trunk liner that best buy sells, it comes in 1square yard. it is kinda thick, still stretchable, and has no backing.   I have used lycra which was very stretchable and worked ok but if you resin is not mixed perfectly consistant it will kinda curl at the edge of the layers creating a lot sanding to do. another thing I found useful, is being fiberglass is flexible in flat areas, put lenghts of rope in the mat, on the inside of the enclosures. I found this to add tons of strength