Using the Asphalt Workshop appears to have moved on
since the dev blog entry, so here's how the version that I retrieved works.
1) Craft the Asphalt Workshop - recipe is 8 Asphalt round the outside, mese shard in the middle.
2) Open the Workshop by right click.
3) Load enough white or yellow dye into it on the left.
4) Move the pattern that you want to the "template" slot at the right.
5) Move a Steel Ingot to the left slot.
6) Watch it make the tool.
7) Move the tool to your inventory at the bottom.
This creates a tool in your inventory. You need to lay some (blank) asphalt, then you can "paint" it with the tool.
Cliff