Aardwolfe:
If you want to have the fun and would like to build one of these Sextants, then you should use the eclipse, or solar shades like the museums have to sell. They can be found at this
website. Click on the link for free stuff and follow the directions. Not sure of international deliveries though.
If you want to do any solar viewing these glasses will help and for the price could be "modified" to use as filters in the Sextant.
There are other ways to view the sun, check out the info on this
link.
Ray W. was right to direct you to use the Arc Welders helmet glass in #14 shade. You actually can buy just the glass for about $10.00 USD. You DO NOT need the entire helmet. Carefully hold the glass to your eyes. I have seen several amateur astronomers use this technique, with success, as they have using the more expensive solar filters for their telescopes and binoculars.
Good luck, let me know if you need further assistance.
Stargazer
"If we believe in absurdities, we shall commit atrocities - Voltaire"