One fairly successful build for Clunk is the extreme health, tank build. In this build, you keep your own damage output quite low, but invest wholly in your own durability. It will take your opponents a lot of time to take you down. Time in which they can't shoot your turrets, creeps or allies, and in which your allies and turrets can destroy them. Later in the build, you get tough enough to tank turrets for quite some time. For this build you first acquire Bite and then put at least one rank into Medical Pump. This is a cheap way to get a bunch of health early on. After three bites your max health will have increased by 75 points. Bite gives you enough damage output to be a bit of nuisance to the opponents. This important in this build, because if your damage is too low, your opponents will simply ignore you. If you see that this is the case, you can invest in a rank of Quick'n Cleaner to up your damage a bit. You'll probably feel slow, so pick up the movement speed upgrade. This makes it easier to get your enemies in range of your Bite. After that, get the second rank of Medical pump, and start buying health upgrades. If you can hold out long enough, buy the large health upgrade first. By this time, you should consider buying Explode, since a Self-destruct bite combo can dish out a whole lot of damage in a short time. Don't worry about the damage Self-destruct does to yourself. You have enough health to cope with that easily.
Standard Upgrades: Health upgrade, Large health upgrade, Movement speed upgrade