Okay so these may not easily be DIY, unless you are very experienced and ambitious. At the very least they can provide inspiration to improve your bachelor pad balcony.
Spaceless Fold-up Table
Need a table on your balcony but have no room? Sandy Lam's brilliantly designed pieces are perfect for bachelor pad balconies with little space. Her collection currently consists of a Bench and Table, both with a "concrete city look". Find more information here.
Another interesting folding table, but this one attaches to your balcony railing. The minimal yet functional design is the draw here; the table itself may be build-it-yourselfable.
Torafu Manufactures the models in Japan with Canadian red cedar. It's portability is convenient and will also prevent theft from jealous admirers. The ideal table for a small bachelor pad balcony with limited room.
Check out the Torafu Architects site for more information (hopefully you can read Japanese).
'Balkonzept' Hanging Table
Urban European design that is also extremely functional. The top portion can hold plants or be used as a beverage cooler. The bottom half is all business; perfect for eating or working on your laptop.
This one we wouldn't consider DIY, and unfortunately it is only available on the German stadtbedarf site. Save your Euros.