big mesh bag or large paint strainer bag.
in a partial mash you are converting starch to sugar via enzymatic action. this "action" happens at around the magic 150° mark. if you boil your grains - they will not convert...and you will not get much if any alcohol and the beer will be undrinkable bitter from the tannins.
you can sparge with higher temp water - around 170° - but for a mini mash keep the grains around 150° +/- for about an hour. get some iodine and check for conversion during the mash. it should be understood that you do not return the test sample to the mash...i know that's probably obvious - but I've seen it asked b4.
when looking for partial mash info on the web the instructions can be spartan to mind numbingly complex. it need not be. it is a fairly simple process that produces great results.
in an extract recipe with grains - you are steeping much like a teabag to extract taste and color
in a partial mash and all grain - you are getting taste and color - but you are also getting conversion as well. in partial mash you should have a good amount of 2 row for proper enzyme action to take place by some instructions up to 50%