Stencils do not work well around curves (e.g. the side of a barrel) - stencil material is necessarily rigid - bending it to a curve will cause lifting within the image area and results will be poor.
Minimum sizes - gaps for areas to be cut and material left for connectors must be large enough to be cut. These must be more than 1.5mm wide. Tiny letters, small and detailed graphics are generally not practical for stencils.
Connectors - all of the block-out sections of a stencil must be connected right through to the outside material. You need to consider how the inner most sections of an image can be connected through to the outside. The addition of connectors will affect the look of the painted image. Consider whether the painted results with connectors will ruin the look of the image.
Lower case letters are less suited to stencil making because they are generally smaller and more compact and they have more centres to be connected - for example - E e, G g - the centres in the loops of the lower case letters need to be connected through to the outside.
Image suitability - complex images with fine lines, images with multiple layers (for example an image that is framed by two outer circles or boxes) may not be suitable for stencil production.
We may be able to produce a stylised version of your image that is suited to stencil production but this is a process of compromise to achieve an image that can be used and which will satisfactorily represent the original image.
The sequence below demonstrates development of a stencil from an original logo. The results still resemble the original logo but are disrupted by the connectors.