[Tony M]

Well my old 650 battery was on its last legs so I brought a new Willard 668 which was on special at Midas (R1,700 incl).
I chose the 668 casing because I found the 650 battery was a little tall and the positive power cable, in particular, was a little stretched with the 650 battery.
However, on tightening the restraining bolts the second 'eye' on the battery tray broke. The first 'eye' had already been 'fixed' by the previous owner using a small piece of sheet metal and a couple of pop rivets.

Looking around on the internet the rupture of these 'eye' on the tray seems a fairly common occurrence. The tray is made from fibre reinforced plastic - where the fibre in this instance seems to be glass fibre and nothing exotic.
Other than replacing the tray with a new one (±R1,150 from the dealers) there were a number of methods people had used to effect a repair, most commonly by just using sheet metal or angle iron with holes drilled in to accept the standard tightening rods.
But tightening and loosening the tightening rods is always a chore so I thought perhaps Velcro might work. A little investigation on the internet reveals that it should be strong enough and if it was good enough to be used on the space shuttles to hold stuff down, it should be good enough for automotive.
I obtained a pack of 50mm wide Velcro, which contained 1 meter of 'hoop' and 1 meter of 'hook', from Outdoor Warehouse this morning for R106 . There are other options available from other stores.. Cutting each length into 2 pieces of 50cm, and joining with a 10 cm overlap gave me 2 straps of 90cm each. These straps fit neatly into the spaces between the tray holding bolts as below (pictured from underside of tray):

Bolting the tray back into place I found that these straps actually slide quite easily under the tray (the tray is slightly raised from the chassis when bolted down) making the final 'overlap' quite easy to accomplish. It might even be possible to add the straps to the tray without removing the tray by sliding them under the tray 'in situ'.
Unfortunately I forgot to take a picture at this stage before putting back the battery but here's the final installation:

The overlap of the Velcro on the top is around 15cm or so but will differ depending on the height of the battery being used.
The only 'negative' thus far is that the battery is just a few mm shorter and wider than the tray so although the battery is held down pretty tight, it can slide sideways.
I guess a small 'mat' of say 2mm thick rubber placed in the bottom of the tray will rectify this. I'll get a piece and see what happens.

Anyway, I just posted this article because it might come in useful for others if they encounter the same problem.
I assume this approach is legal but if anyone knows/thinks otherwise, please let me know.

Cheers,
Tony