I'd love to produce a painting for your Sister, I'd like to paint digitally and have the print professionally printed by the printers I use on your choice of medium eg canvas or giclee print and then couriered to you.
If you'd like to take a look at my portfolio on freelancer you'll see examples of the illustrations I've produced, most are children's picture book pieces - but it will give you an idea of style. I feel confident I can produce a beautiful illustration for you - if you'd like to include personal details such as your Sister and her partner I can do this, or more subtle things, eg maybe a animals they like etc.
I'd love to discuss further if you are interested,
https://www.freelancer.co.uk/u/heidiolivia
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Thanks
Heidi