Thanks Pete, Stainless - I will take that as an endorsement of the MDF strategy.

In terms of volume; its tapering towards the bottom so its an odd shape - I will do the math now its physical and I can take measurements of what actually fits but I figure I could also put a plastic bin liner in it and add water to validate. I am aiming for 2 - 3 US gallons (the small 4 litre ones, not our are manly 4.55 litre gallons).

If I have calculated and converted my air consumption (at 14:1) and accounted for the specific gravity of the fuel correctly I am estimating 3 litres per run so 2 US gallons makes sense? Its a 2 litre, naturally aspirated and assuming 8,500 rpm.