There are videos on youtube of people lining wooden molds with freezer paper, they are much better at it then me.
I've cut up those thin cutting boards, taped them together and line my molds as well as trying it with coroplastic (at home depot). So I've got those in my mold (I leave them in all the time to make my molds smaller), and I've used them without lining, BUT I find it a pain, the sides stick sometimes, and maybe its because I try and unmold too soon, could be my recipe...who knows, but I've gone back to lining the liners with freezer paper.
Also, the coroplastic has a ribbed pattern on it and it shows up on my bars, which im not a super fan of.
And all my wooden molds have soap stains on them, from where the soap touched at one point....its the sign of a well used mold, haha
I think Im going to finally drop the money and get molds from SilverMoon or SoapHutch!!