Power bank multiple output currents
First you need to boost the 3.3V to 5V, that can be done with a boost converter (Wikipedia). After that you'll have a 5V rail. 

Now build 2 current limiting circuits one at 1A and the other at 2A. Building a current limiter is pretty simple with a linear voltage regulator and a few surrounding components. There's an example on how to do it with a LM317. Figure 23 in LM317 datasheet shows an example of how to make a adjustable one. The LM317 is not the most efficient regulator but it will give some ideas. You'll have to do some research to find the most suitable for your application.