As Stan Laurel once said—You can lead a horse to water but a pencil must be lead.
While this is obviously a joke, it is true that certain people (like me) can be genetically unsuited to using pencils for practical work. This is because now that I have lost most of my hair I can no longer get a pencil to stay in place behind my ear …which as everyone knows is an essential skill for any self-respecting tradesperson.
The result of this acute inability is that I am forever losing pencils and can often get through a dozen on just one job.
Fortunately IKEA seem to have more than they really need and they never seem to miss a few. It is however a very high price to pay having to endure a trip around IKEA just to procure a few pencils.

Fitting showers is not the easiest of jobs but there are things that can add to the difficulties of containing the water within the enclosure  ..and nobody likes water leaking out of their shower.

1) Try to avoid cheap enclosures. The manner in which enclosure profiles fit together, the method of sealing the glass panes and also the number places to be sealed with silicone vary greatly. From experience cheap enclosures often lack the design finesse of better, more expensive makes and sometimes I’ve seen poor factory assembly of the units.

2) Some shower trays (usually the ones called cast stone trays) do not have a film covering. Such trays are often greasy I presume from some vaseline-type release agent to assist with getting them out of the mould where they are cast. Unless this grease is removed totally, the silicone will not stick and so a seal around the edges and across the front of the enclosure will not be achieved.

3) For some reason clear silicone is rarely as good as white. If you need to use clear (which you often do) get something like Forever Clear made by Everbuild.