Variable infill density in Slic3r?

Hi guys,

I'm printing out a new extruder drive block as the hook on the original one snapped. I printed the part at 70% infill with 3 perimeter layers. My thoughts were if I had denser infill then the hook will likely be more durable. Is it possible to have configure Slic3r to fill in only the book area with 70-80% infill whilst the rest of the part stays at 30%? Means I don't waste material on unnecessary areas of the part and it will be a bit lighter too.

Image of the part in Slic3r


Thanks

[slic3r.org]

This should help

Most of the strength of a part such as that is in the skin, so greater infill does not make a great deal of difference regarding strength, and in fact could make things worse for parts that need to flex because higher infill makes the part less flexible. I am surprised that you have found the hook to be weak - it's plenty strong enough on the one I've printed - the weakness is in the filament guide which tends to adrade until the filament eventually wears its way completely through and jams. That's why I use the modified extruder block where the filament guide has a larger diameter so as to take a PTFE tube to act as a lining.

Dave