You could try one of these,
It is a Nest box warmer for rabbit kits and will keep surface temperature between 95 and 100 degrees F, you can add some sand to the nest box to block some of the heat from the eggs.
Note you will need to have a nest box that is around 9" x 17".
http://www.bassequipment.com/Miscellaneous/Rabbit+Nesting+Equipment/default.aspx
Chris

It is a Nest box warmer for rabbit kits and will keep surface temperature between 95 and 100 degrees F, you can add some sand to the nest box to block some of the heat from the eggs.
Note you will need to have a nest box that is around 9" x 17".
http://www.bassequipment.com/Miscellaneous/Rabbit+Nesting+Equipment/default.aspx
Chris