errm hmmm, something to be prepared for: normal fabric absorbs your sweat and allows it to evaporate. plasticky materials stop it evaporating and make you all sweaty and horrid. no matter how much you think you don't sweat, i assure you that wearing plastic clothing you may well find yourself wrong!
as for actually making it, look at a skirt you want it to be like to get an idea of how to make it.
remember that duct tape probably doesn't machine-wash!
my internet connection is being temperamental and not letting me see your picture, but i'm sure your robot is charming.
i have made a couple of robot toys - they had such gadgets as wheels (made from buttons impaled on bamboo kebab sticks), squeakers, turning heads (a complex 'wheel and axle'-type contraption utilising a straw and another kebab stick), and bendy pipe-cleaner arms.
i have only ever seen steel ones. frankly when it comes to circular needles, i consider myself pretty lucky if i go into the one shop in my city centre that sells knitting needles, and it has the size i need.
as i don't know of any free patterns in that yarn, i would suggest something like a shawl or scarf where the guage is not terribly important, and where you can stop if you run out of yarn, or carry on a little longer if you have a little left over.
yep, just plain knitting back and forth is boring. that's why some knitters go crazy with cables and colours and fancy stuff and end up making something that you would never actually wear. when i am thinking up something to make (not being a fan of patterns, which usually look too old for me), i have to balance making it interesting to knit with keeping it simple enough that it will look good as a garment!
i don't knit with wool, but i can't imagine that both your guage and the pattern can be correct.
check your guage somewhere on the actual garment you knitted. **** i am guessing that this is probably where it went wrong, frustrating as it is to have to admit it - your guage may not be constant
check that you executed the pattern correctly.
if that is ok, then maybe check the pattern for mistakes. eg check that the guage is plausible for the garment's measurements - ie if the back is supposed to be 20 inches across, at a guage of 20 stitches over 4 inches, then you would expect it to be about 100 stitches wide.
if all that is correct and you can't get it to the right size by blocking then the person who wrote it must be daft. perhaps you could give the sweater to a child of about the right size.
that looks like a gathered strip, more than a group of petals.
i would try knitting a strip which is much wider than it is long. then when you are done, instead of casting off, cut the yarn, leaving a length a bit longer than the width of the knitting. then pass the yarn through the stitches and pull it, so it gathers the knitting up.