Dropping a brake calliper position.

After a miscalculation (or lack there of) on fitting a Shimano 105 5800 calliper to the rear bridge of a TF Dart v1 it turns out the reach is too shallow by about 8/10mm. Now, I could sell the callipers on and get some long drops but in the spirit of the bodge/hack and the quest to have a better mechanical understanding of my bike (currently near zero) I've decided to try and make an adapter.

I've looked at Sheldons fix and wondered it anyone had some advice on making a more 'elegant' solution? I thought of 3d printing but was not sure about the strength and have never used it as a process before.

...For the record I'm a very light rider (56kg) and the front calliper works perfectly so this is unlikely to be placed under an incredible amount of strain.

Thanks guys

Plastic 3d printing or something less likely to kill you?

Polycarbonate plastic was what I thought of in the first instance.

Obviously it's dependant do the nature of the design but would that be a risky move?

It'll rip off at first use. Rotational mass of the wheel alone would annihilate it. I wouldn't even trust a 5mm steel stock to stay static. Get a long drop caliper.