Welll if she was a fully mature adult when you found her, then there is no way to be sure that she hasn't already mated.
With a large sling or subadult, you can use a plastic cube like the recycled "cube o death" (from a Sarr. I picked up at a BBS while ago). These can also be found at hobby shops like Michaels. A very small drill bit (I used a 1/16 bit) can be used to make a series of clean holes for ventilation. However, I do not know if a newly hatched Latro. spiderling can squeeze its little body through such a hole. And being that you might not want an invasion of Latros in the house, that leads us to......
Pretty much any large plastic container with a tight fitting lid. Could be a container from a large jar of pb, pretzels, cheesepuffs, etc. Thrift stores like Salvation Army and GoodWill are often great sources too. My favorite find so far were some plastics storage canisters (like the ones folks often use to store flour, sugar, etc in the kitchen) with flip top lids I picked up for a buck a piece. Drill some large holes (I used a 1/2" bit) in the bottom of the container. Cut a piece of fine meshed cloth -- like tshirt or pantyhose material -- to fit the bottom of the container. It doesn't have to be perfect, just so that it will completely cover all the drilled holes. Now glue the cloth to the bottom of the container. Doesn't really matter if you do it to the inside or outside. I do the inside so I don't have to worry about anything catching the material and tearing it off. Especially if you're using silicone or a glue that releases a lot of fumes as it cures leave the lid off to help the fumes dissipate. Once that has cured, I glue a stick or several of them in the bottom of the container -- hot glue works well. While it isn't necessary, I feel it gives the spider some easier attachment points for starting its web. Put your little charge in her new home and close the lid. Once it appears that she is starting to explore, slowly turn the container over so the lid is now the bottom of the container. Since members of this Family commonly lay silk wherever they go, she shouldn't fall when you turn the container upside down. She will make her "widow's bower" somewhere at the top of the container -- where the sticks and vent holes are. Having the lid now as the floor/bottom will make it easy for you to remove the remains of her meals.