> Have you looked in a local $2 shop (or your local equiv) for cheap
> magnifying glasses?
> Also I have seen credit card sized frenel type magnifiers used as
> advertising giveaways. If you could use them & find a source they
> should be well inside your budget.

1.
           www.alibaba.com
            www.madeinchina.com
             www.ebay.com :-)

2. You should have little difficulty casting your own. Machining from
plastic stock a possible low volume if you have access to a tame NC
mill - more work.

Look at various LED lens shapes and compare radiation patterns. After
a while you will be able to hazard a reasonable guess as to beam width
from lens shape. Start with a tight beam one and replicate it in
general terms. Play. There are some resins available which are
intended to make optically clear plastics - used by eg hobbyists for
encasing Dandelion seed heads and the like.

I've "made" a few rough LED lenses by hacking the end off LEDs and
smoothing the remainder. Worked gratifyingly well. Avoid removing the
die while cutting :-). In one case I used a cut off LED lens &
reshaped it for another task. All quite roughly done - results tend to
be better than expected.



 Russell
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