What you need is 6 red felt squares, a marker, and some thread and needle. Our goal, is a block of tnt.

Step 1: Making It Tnt.

Now, you use the marker to write TNT on all of the felt pieces, on just one side.

Step 2: Making It a Block.

Then, you sow it together, so the writing faces out. You have two squares on the top and bottom, and the other squares connect to both at the same place, then sow the 4 remaining edges together. And presto, you are done. Easy, but with a nice result.