Element collecting is the hobby of collecting the chemical elements and (usually) displaying them in a periodic table-like shelf.
Most elements are stored in either bottles or sealed ampoules to prevent oxidation, in case of elements that are more reactive or to prevent them from leaking (bromine, iodine). With the exception of fluorine (though this gas can't be ampouled due to it's rapid reaction with glass and most metals) and chlorine, all the other gases are colorless. To differentiate their properties better, hydrogen, oxygen, nitrogen and noble gases are sometimes stored in a special gas-discharge tube, where each gas will glow in its respective spectral color when an electric current at high voltage is applied. This is done by ampouling the gas at low pressure, then putting a high voltage through it to produce a spark. Sometimes this method is also applied to alkali metals.
Many elements can be easily procured from hardware stores, such as copper from copper pipes, iron from steel, carbon from graphite rods, magnesium from pencil sharpeners, lithium from lithium batteries, etc. Other can be easily made from readily available chemicals: hydrogen can be made from electrolysis of water, reaction of acid or alkali hydroxide with aluminium; chlorine can be made from bleach; iodine can be extracted from iodine tincture; boron can be obtained by reducing boron trioxide, often with magnesium.
Purer samples of elements can be acquired online. Always check the legal status of the element you acquire (ex: mercury in EU, iodine and phosphorus in US). Radioactive elements are the hardest to acquire, as some require paperwork or have a half-life too short to be isolated. One way around the latter is to have a source of mineral that contains traces of the said radioactive element (ex: polonium traces in pitchblende). Pure depleted uranium is available from United Nuclear, but it costs about $20/g and it only ships in United States. Radioactive materials can sometimes be found on eBay, but most commonly, these are uranyl salts.
Metallium sells all stable elements to collectors, including the rare earths, halogens, and white phosphorus.