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 easily be ampouled due to it's rapid reaction with water and reaction of the resulting hydrofluoric acid 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. As an alternative to expensive ampoules of fluorine, fluorine gas is naturally found in some types of fluorine mineral, namely antozonite, where it is found in its inclusions. Breaking this mineral releases fluorine gas which rapidly reacts with oxygen and water to form ozone.
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. Occasionally one might find raw iron from the thermite welding near railways, though this source may have plenty of slag. Some elements can be found in scrap electronics, such as silicon from various dies, germanium from old transistors or diodes, gold and silver from fingerboards and electric contacts, or rarer platinum, while iridium spark plugs have a small tip made of iridium metal. Other elements can be easily made from readily available chemicals: hydrogen can be made from electrolysis of water, reaction between an acid or alkali hydroxide with aluminium or another metal; chlorine can be made from bleach and hydrochloric acid; iodine can be extracted from iodine tincture; boron can be obtained by reducing boron trioxide, often with magnesium; oxygen can be obtained by adding manganese dioxide to hydrogen peroxide. Purer samples of elements can be acquired online.
Metallium sells all stable elements to collectors, including the rare earths, halogens, and white phosphorus.
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.
For European chemists, Onyxmet is a very good source, and you can find almost any chemical element being sold there.
Fluorine ampoules can also be acquired from suppliers like Onyxmet.
Always check the legal status of the element you acquire. For example, mercury in restricted in EU and a few other European countries, while iodine and phosphorus are DEA List I in the United States. Cadmium and thallium are also difficult to acquire in pure form, as many countries regulate the sale of these two toxic metals. In Australia, platinum is classified as Category II precursor chemical and purchasing it requires and EUD. Radioactive elements are the hardest to acquire, as some require paperwork or have a half-life too short to be isolated. Certain elements, such as polonium will most likely draw the attention of the authorities, especially after incidents such as the poisoning of Alexander Litvinenko. One way around the latter is to have a source of mineral that contains traces of the said radioactive element at any given moment (ex: polonium traces in pitchblende), as most minerals aren't restricted. Uranium, regardless of enrichment percentage, is restricted in the EU without proper paperwork, while in the US it's legal to own up to 15 pounds (~6.8 kg) of "un-enriched source material" for educational, scientific, or industrial use.