We've gone as far as getting little 1 gallon ice buckets, or tupaware bowls to put guppy fry in until they are a couple of weeks old. If you have a 5 gallon bucket set it up with treated water (if you are on a municipal system) toss a plant in and put the fry in there. Just be sure the bucket has never had chemicals in it and is food safe. (if something is food safe 99.9% of the time it is fish safe, I do believe) We use several 5g buckets to do waterchanges into so if we leave them with water in them when not using them they grow microfauna and work well for baby holders.
If you don't have safe buckets, try big bowls. A lot of people will 'poo poo' the idea of using bowls, but if ya gotta ya gotta.
Best of luck with your babies.