Build or buy

I am glad to have found this: foam crown molding. I am planning to build a reading nook for my wife who loves to read before sleeping especially during weekends. I plan to place it by the window. I just need to convince her to trust my carpentry and arttistry. She prefers to buy ready made things while I like to build them. Sometimes, we do not arrive in an agreement thus nothing is accomplished. Well, no one wants to give in? Sometimes she tells me to build a third floor where I can do everything that I want. Now, that would be more expensive.