Find an old pair of natural color or sheer white/gray pantyhose and trim the "feet" off. Carefully fill the hose with cotton or cut up cloth (old bed sheets work well for this). If you want to give a really nasty view, add shells or other "sharp" looking objects. Using a hot glue gun seal the ends. Draw "Veins" with a red marker
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Hot glue corpsing. I have done this although messy the results are perfect for cheap props to hide their lack of realistic gore.