Smoker -- You'll need to purchase a couple stacks of large blocks, smoker sketches, and flasks of water. In the pottery wheel, place one of each and hit combine. It will produce an unfired smoker. Destroy it as it won't sell (unless you want to spend more money on firing sheets to fire it up in a kiln). This will take you to a skill level of about 82

Medium Bowl -- Requires a block, medium bowl sketch, and water flask. This will take you to level 122.

Mixing Bowl -- Requires 2 large blocks, large bowl sketch, and water flask. This will take you to level 128. You can probably stop at this point and still succeed with the potions, or move on to the next bowl to be certain.

Large Bowl -- Requires a large block, large bowl sketch, water flask, and glass shards. This will take you to level 148.

Now that you have your skill up, combine in the pottery wheel 1 small brick of velium + 3 crystalline silks + 2 glass shards. This will result in an unfired velium vial. Now go to the kiln and combine the unfired velium vial with a high quality firing sheet. This will result in a velium vial.

In Thurgadin find Frundle Frenkler. If you are coming out of the bank, turn right and go down the ramp. She is in the middle building on the left. Ask her about velium vapors and she will give you a velium purifier.

Inside the velium purifier place 2 small pieces of velium + the velium vial. And here you have your gate potion!