I saw a stamp which will render text unreadable but it's not cheap either. So I decided to make mine for less than $2.00
Step 1: Materials Required
1. white hi-polymer eraser (or any eraser with surface 65x25mm) from a stationery shop
2. a piece of wire about 10cm long and 1mm thick (2mm preferred)
3. a soldering iron
4. black ink
I chose black calligraphy ink, also from the stationery shop (ink $0.55, eraser $1.00SGD)
For inking I used a pep-bottle cap and stuffed it with a piece of dish-washing scouring pad. Dab the ink on the stamp before use.
Step 2: Making the Stamp
2. Adjust the ends to have a gap of about 3mm or to your preference.
3. Heat up the the soldering iron, be careful not to burn yourself.
4. When the tips are hot (test on eraser), dip them about 3 to 5mm into the eraser to create dots.
5. To draw lines, press the wire tips onto the eraser. Move slowly to engrave lines of about 3mm in depth. Redraw if necessary.
6. Use finger to rub away the unwanted fibres of the melted polymer.
Note: the pattern drawn need not be neat, the messier the better
Step 3: A Stamp Is Borned
Step 4: Stamped Result
Dab the eraser with this ink pad and it is ready for use.
How's the result.... good enough for me.
No more shredder, lesser carbon footprint for mother Earth. Moreover, non shredded papers are easily sent for recycling compared to bagful of "spaghetti"