Hi - If you use the correct epoxy you will not need to vibrate. Vibration leads to segregation which is not good. The epoxy should be very thin like used for river tables and infusion. With this sort of resin you can dry pack the mould and pour the resin in until filled. Laminating epoxies are desigbned to get thicker when agitated. They have thixotropes added for this purpose so they do not run. Peter