I saw this tip a little while ago while watching Robin Fitton on his 'grunts' you tube channel.
Robin was using the gel to base up his 15mm sci-fi figures. I will see how I get on with it, so far so good. These large 80mmx60mm bases have a lot of wide open flat space to fill and this gel could be the ticket.
I will use the gel as the first layer to add some contours to the base. Next up will be a little sand and then flock...you know the drill.