Rubbermaid/Sterilite containers are great! I use them as quarantine enclosures. And you can get them at Walmart/Target.
How big is your blood? These snakes need an adequately large enough enclosure to sprawl out to prevent respiratory problems. Blood pythons' lung is just MASSIVE and they need more room than some. But even for an adult a 4ft by 2ft by 15in tall is perfect. Too small a snake and too big an enclosure will stress them out and can get you the "strike and no feeding" response that your getting. These snakes are known as enthusiatic feeders. And when they dont eat, that can be a sign of your husbandry being off.
Secondly, a tub will help with some of your husbandry. These snakes need 86 to 88 on the hot side CONSTANTLY. 78 to 80 on the cool side CONSTANTLY. And humidity of 60 to 70% CONSTANTLY. As well as an overall cage air temperature of ~80 degrees They're not as forgiving as other species and little mistakes can cause big problems.
I will ask if you have any pictures of your snakes' belly? If its turning black then thats not good at all. That could be scale rot and would need to be taken care of asap.
Hope this helps.