Using a pare of pliers rip out the solder from the bottom of the bulb. Next break the purple glass insulator. Nest using a screw driver, stick it down the bulb and break the insides and smooth it out. If the bulb has the white powder in it then just wash it out with water a few times and wipe it with toilet paper or a tissue to clean any residue left behind.
-=theres a small glass tube inside I think used for evacuating the air, if you save this and melt down the broken edges a little you can use it as a mini test tube=-
-=The purple glass is very sharp as well as the rest of the glass to be careful, you may want to put gloves on for this part=-
-=leaving the metal base is optional but recommended, it will break easier if you remove it and cannot be clamped onto a stand=-
Now that you have cleaned out the inside your going to want to make measurements. Using a pre-labeled container fill it with water to the amount you want your measurements to go by. eg. lets say I want to make it go up by 10mL's, I would measure 10mL and pour it in the bulb and mark it with a sharpie, then i would do it again until i reach the top (150mL). If you use sharpie it will rub off after a while and you will have to re-mark it if you want to make measurements with it, although i dont know of any other thing to use.
By this step (if you followed the others) you have finished your flask but I have a few things to say about it. First, because the glass is thin and wasn't made for use in chemistry it cannot stand up to the conditions that real flask can. If you heat the glass to hot and quickly it will crack and become useless for this purpose. If the flask contains a liquid it is much less likely to break from thermal shock but you should still heat it slowly just in case. If you decided to keep the metal base then I'll go over that to, because the metal is much stronger than the glass it allows you to put a clamp on it so you can put it on a stand. The opening on the base it much smaller than the opening on the glass and slows the spreading a vapors coming out of the glass. One last thing, I dont know if you can fit a tube onto the base but i do know that you cant fit one on the glass, nor can you fit a ground glass stopper because its to thin and and wont be perfectly round.