Most sailplane airframes are built tail heavy. This means that in order to achieve a CG position that will allow said airframe to fly, a great dollop of lead will have to be inserted up the snout to redress the balance. Now, if the model has a short moment arm, and you wish to add as little lead as possible to keep the wing loading down, it would be sensible, would it not, to insert the lead as far forward as possible to allow it to have the utmost effect. Now, I use polyester body filler for the nose block for two reasons:

	1. It is heavy enough to add weight of it's own
	2. Before setting, it is malleable enough to flow into the spaces in the nose area and fill them up completely.

Additionally, this system allows you to screw chunks of lead to the front side of the first former (thus effectively lengthening the moment arm) and then to allow the filler to flow over the lead, locking it all into place. If the model is large, you will need to do it in stages, as the weight of a large amount of un-hardened body filler will be profoundly affected by gravity, allowing unsightly bulges to develop which will then need correspondingly large amounts of elbow grease to get rid of. The best way to achieve the desired result is to glue in plywood profiles, both horizontal and vertical to give the filler something to lay on and which during the sanding process will give you something to shape to.