I have created a selection of greetings cards based on my collection of tiny British wildlife ornaments, which you can download and and print for free! Just click the picture of the animal you'd like to print, then 'Go to link' for the option to download and/or print the PDF.
The cards are designed to be printed on A5 card and are A6 portrait size once folded, requiring a C6 sized envelope (you could always print on A4 card for an A5 sized card once folded, requiring a C5 envelope, but the style of the pictures suit a smaller card).
I recommend using a high quality card stock, preferably recycled, suitable for printing (it doesn't need to be glossy card) of 350-380 microns thickness/270-290 gsm weight. I have printed on brown Kraft card in the past and they do look ok, but aren't very bright (fiddling with printer settings can improve them, but I don't know enough to be able to guide you in this properly). A lighter coloured card is better. Make sure your printer is set to A5 paper size, landscape orientation and high quality colour print.
Once printed simply fold the card in half and write your greeting on the inside. They would also make delightful gift tags.
Polite Copyright notice - Please keep in mind that these designs are entirely my own (and took me a long time and a lot of care to create). I have put them on here for your own personal use and you may print as many pages as you like, but I do not give permission for the images or PDF files to be shared, copied, sold or altered in any way.