When looking for 3 point harnesses I was after something light and not exorbitantly expensive. I found what I was after, $44 off eBay and 953 grams (2lb 2oz). Using the cardboard template method of design, I came up with a shape for the lower seatbelt attach points. They have been set at station 3 and tilt inwards to better transfer forces in a direct line with the seatbelt rather than pulling the mount inwards with any sudden jolting on the mount.