Reuse birdseed bags into hiking or biking bag

You know those birdseed bags that are like woven plastic cloth (called woven polypropylene)? I wanted a bag to carry my phone, keys and water bottle when I go hiking or biking and so I came up with this. Is it particularly attractive??? No. But super useful for carrying and waterproof if I get caught in the rain! I first cut out enough of the bag to easily fit around the water bottle. I sewed this wrong sides together into a tube shape. I folded up the bottom and hand-sewed it shut with a curved tapestry needle. Next I made the straps by using a zigzag stitch on strips that I folded in half. I measured it so the water bottle would be at hip level. I hand sewed some hair elastics to either side of the bag and then looped the straps through and sewed them this allows the bottle to pivot easily in the straps as I walk or bike. Next I made a simple pouch for my phone with a flap that comes down and over. I cut a rectangle out of the middle top of the pouch so that when I open the flap I can easily get the phone out. I sewed velcro to either side of the triangle and the soft velcro part to the flap. This will protect it from getting wet. I then sewed this pouch onto the water bottle holder down the middle of the back of the pouch using the curved needle again by hand. Almost done! Next I sewed the sides of a triangle together to make a cone with another flap on top to close. This is to hold my keys. I sewed velcro onto the outside of the cone and the inside of the flap so my keys will also stay dry. I sewed this cone onto the other side of the water bottle holder. Done!! My only suggestion is to use perhaps metal rings or multiple elastics for the loops that the straps go through. One hair elastic doesn't look like it will be strong enough. Happy sustainable hiking and biking!!