Here's some really good info on Tanks and substrate for O scyllarus from Gonodactylus
Gonodactylus said:In the field the burrow of a 4 inch O. s. would be about 10 inches deep and 14 - 18 inches long. It is unlikely that you could recreate the substrate conditions that would allow the animal to construct such a burrow in an aquarium. Some large pieces of live rock along with lots of smaller pieces and some gravel is probably as close as you can come. The substrate should probably be at least four or five inches deep, but the major support for the burrow will come from the live rock. The animal will fill in the gaps with smaller pieces.
As for size of aquarium and glass vs. acrylic, the largest O.s. I would keep in a 10 gal. aquarium would be about 3 inches. This is not because of the risk of breaking the glass, but because of the bioload that might occur. While it is possible that a four inch O. s. could break a 1o gal. glass aquarium, it is highly improbable.
As for glass vs. acrylic, the major difference is that the plastic is pliable. I have several plexi tanks that I keep O. s. in and while they are dented by strikes, they do not break. Glass will chip and occasionally crack. If the stomatopod is over 4-5 inches, I would advise acrylic or at least 7 or 8 mm glass.