Two sub-forums, one for material reviews, the other for tutorials.
Of course, this is the second suggestion I've made, though the
first one about a forum dedicated to original props and costumes may have been too far out for its own validation. But the suggestion I'm about to make may be more useful for RPF members.
As you know, one of the things about making props is the constant trial and error on what materials to use. If you've noticed, I myself have asked questions about certain products in the actual prop replica portion of the forums. If others also do so, using the search engine would end up resulting in too many posts to look through just to find out about one product alone.
So, I suggest that one sub-forum be open under the main forum section which is to be dedicated strictly to the reviews of products for making props and/or makeup effects. For example, let's say a user wants to know about mold-making kit from a certain company or the best type of paint to get the best kind of look from a prop. If any users here have used the product, they can post a thorough review, explaining the pros and cons of the product and if it is worth the price. For example, which clay is the best for sculpting with the best detail and it not cause any problems when you create a mold.
Another sub-forum, which could come in just as handy, is a tutorials sub-forum on how to not just use materials, but methods of constructing props. This could be useful for people who are going into constructing physical props or creating makeup effects. Though some tutorials are available on YouTube, such as how to do a two-part mold, for example, there are a variety of others that do not have tutorials, such as alternate methods of making a life cast of someone's head to be able to make certain makeup effects or how to scratch build a studio grade stop-motion armature. And not only it cover the construction of props, costumes and models, but also ways on how to display them (again, the product review section could be useful here, as it could also cover the best display cases or materials to construct a study display case that won't cause damage to your props, costumes and models {be it screen-used props or replicas}). And not to mention, if someone finds a tutorial on how to construct an item that appears pretty high quality (like from Instructables or YouTube), they can post links to them, essentially becoming a resource of tutorials for constructing props and methods of how to do it.
I hope this suggestion is useful. Thank you for your time and you have a nice day.