A method and apparatus for the production of reinforced plastic objects uses a body form around which a casing having a cover is placed. The cover includes two cover units which between them defines an opening having an adjustable size and position. The opening provides access into the body form so that reinforced plastic material may be applied therein. The size of the opening is minimized to reduce the amount of environmentally harmful substances escaping therefrom, such as styrene. The position and size of the opening relative to the body form is adjustable to provide a convenient access into the body form.