Step 1: Tools and Materials
a strip of thermoplastic, because we will be will be using heat to form it. Mine came from the cover of a defunct printer. Dimensions are not critical, can be changed to suit what you may have to hand.
a small lens, salvaged from the optical unit of an old DVD ROM drive ( mine is just over quarter inch diameter)
various drill bits and a drill.
a heat gun
scraps of wood
I have also shown a fine tooth saw and a block plane which I used to cut and clean up the plastic strip.
Step 2: Drill the Hole for the Lens
Then drill a hole on the same centre a tiny bit smaller. In my case 15/64"
We should end up with a stepped hole, and the lens will sit on the ledge. Test fit the lens, but do not glue it yet.
Step 3: Forming the Plastic
Now clamp the plastic strip in place, with the lens hole centred on the mark.
Now for the heat forming. If you don't know much about the properties of the plastic then apply gentle heat at first, and increase until the plastic goes soft enough to bend. A glove is useful here, to protect the hand doing the bending. We are aiming for a U shape. ( you might want to cut the strip to a suitable length before this step - I only realised halfway through the bending!)
Step 4: Fit the Lens
Step 5: Using the Lens
Photo 1 shows how close the tablet camera can focus. Photo 2 shows a close up of the same pen, taken with the new 'macro' attachment.
Not great optical quality, but interesting to play with, and made with all salvaged materials!
I hope you enjoyed reading this, and maybe you will be inspired to do something similar.