1. Navigate to your shop's Settings and click on "Shipping and Delivery"
2. Locate the Packing Slip template and click on Edit.
3. Copy the following code:
{% for p in line_item.properties %}
{% assign hidden_property = p.first | first | replace: '_', true %}
{% unless p.last == blank %}
{% if hidden_property == 'true' %}
{% else %}
{{ p.first }}:
{% if p.last contains '/uploads/' or p.last contains '/assets/' or p.last contains '/products/' %}<img style="width:50px;height:auto" src="{{ p.last }}"/>{% else %}{{ p.last | newline_to_br }}
{% endif %}
<br>
{% endif %}
{% endunless %}
{% endfor %}
4. Paste the code that you just copied underneath the SKU in your template: Around line 132 if you are using the default template.
5. Save your changes