Hi , my names Ryan and Im senior technician for mould making and casting at Nottingham Trent University , UK . If you could give a little more information on what the sheets will be used to fabricate i may be able to offer a bit more assistance . Ideally i would not reconmend casting a sheet from resin as all kinds of factors will effect the result including shrinkage , discolouration , debris and unlevel surfaces and overall average thickness differences . Cast acrylic is more expensive than extruded sheet material because it is usually cast under strict regulations for on thickness . E . g you can rest assure 3 mm cast acrylic would be within 0 . 05 mm tolerance . Generally , polyester and epoxy resins are going to be too brittle to work with and cut nice shapes from without shattering and can give sticky finishes . Polyurethanes smooth cast range , you mentioned from benamsmooth on could give a better result but clear versions are not to be toyed more so than their opaque yellowywhite friends , if you don ' t know what you ' re doing and dont have a safeventilated area to work due to the exposure limits of the known isocyanate sensitizer . If you have use of a laser cutter i would bite the bullet and fabricate your shape from cast acrylic sheet for a high shine finished result . Similarly if you ' d like blue running through this randomly you could sandwich a layer of polyester pigmented resin in between 2 thinner layers of acrylic sheet . Materials of all kinds can be encapsulated this way and then cut to farbicate all kinds of things . The bowling ball prop seems a straight foeward job . Pick a bowling ball , create or get a 2 part siliconegrp jacket mould made with a pour hole in the most imcomspicuous area . Swill various pigmented polyesterPU resins around inside the mould and to create the marble effect . Finally , fill with either a rigid or flexible expanding foam . I ' d reconmend looking at mouldlife . net if you ' re UK based for variations of difderent density PU foam systems . If you have any questions , require further help or want to farm any jobs out as commisions then just contact me . I have years of experience in various work such as architecture , film , theatre , toy prototyping and product design ! CheersRyan Youngryan . youngntu . ac . uk