Composites processes are generally low cost with regards to tooling and equipment costs, depending upon what process is used for comparison. The flip side is that the processes are labor intensive and the quality is operator dependent. The room-temp cure resins allow for working time windows that must be monitored so that the work is complete before the resins get hard. It is one of those things where you only get one chance to get everything in place and the resins and glass consolidated before things are locked together permanently.
The forgiveness is that there are ways to repair the laminate with additional time and money. There will be grinding and dust and reworking something that could have been done better from the first time.
Repairing will not look as nice, nor perform as well as a properly planned and completed first attempt.
Safety is something that needs lots of attention. The processes are very operator dependent and we are working with chemicals here, so workers must be protected. Many of these chemicals are regulated by several government agencies. This is why these chemicals are generally difficult to obtain on the street.
The styrene-based polyesters and vinylesters require respiratory protection and skin protection, as styrene is considered by some (California) to be a possible carcinogen. There is a time weighted average for breathing the esters, specific to the percentage of styrene in the mixture. Excessive inhalation can lead to headaches, sinus irritation, and watering eyes. Skin contact is permissible, but can be difficult to remove and can enter the bloodstream.
The epoxy-based resins are more forgivable with regards to respiratory issues, but dermal protection is much more important. Short term occasional exposure is not serious, but can develop into allergic reactions.