First, let's look at what the burrows are like in nature. The burrow of a pair of 22 cm L. maculata would be about 8 cm in diameter. One entrance from which the male hunts would be an almost vertical shaft (tipping slightly away from the main burrow) about 25-30 cm deep. The second entrance is usually closed but occasionally is opened to allow the female to hunt, for excavation, or to provide ventilation. The main part of the burrow is horizontal connecting the two vertical shafts and can be from 2 to 5 m long depending on substrate configuration. In sand they are typically long and straight, but on a reef flat with lots of buried rubble, etc. the burrows are often shorter and not as straight. The male spends much of his time in the vertical shaft with his eyes and antennules in the entrance. The female usually stays in the horizontal burrow caring for eggs. Unpaired immature animals (15-17cm or smaller) usually have a simple near vertical burrow with a single entrance and expending down a meter or so.
In an aquarium setting, the ideal burrow for an adult pair (22 cm) would be a horizontal pvc burrow about .8 - 1.3 m long and 8 cm diameter placed on the bottom of the aquarium with enough sand above it to allow the animals to dig a vertical shaft on one or both ends. The sand depth should be of a depth near that of the L. maculata male's length. I've kept several pairs in this type of set-up and they do quite well opening and closing the burrow as they would in the field, breeding and producing eggs and larvae. I have one pair that have been in such a burrow for over 10 years. With a bit more work, you can fit a window in the side of the horizontal burrow to allow you to watch molting, feeding and reproductive activity.
You can also establish single large animals in such a pvc system, although it is easy to give smaller animals a deep sand bed and allow them to dig their own burrow.
If you don't want to construct a burrow with deep sand covering it, you can use just a horizontal length of pvc pipe. I have one pair of 32 cm L. maculata that have been in a 1 m piece of white pvc 10 cm diameter pvc. They are in a 80 gal aquarium with about an inch of sand/gravel/rubble substrate. There are a couple of rocks wedged against the burrow to keep it in place. They have been living like this for over 8 years and have reproduced several times. This seems a suitable option for large pairs, but I've found that smaller single L. maculata generally don't like pvc and often refuse to live in it. All of the larger animals that I have tried accept it.
For more details, see my two part article on lysiosquilloids published in CORAL a couple of years ago.
Roy
I'll have to reconsiture for now until I get a proper sized setup. My hieght is only 8 inches to work with (the hieght from bottom to the overflows) which is not suitable apparently. 
