Personalisation
A customer types their name and sees it on the product. Not next to it in a text box, but on it, following the curve of the surface, in the position it will actually be made.
That is what personalisation does, and it is the difference between "we will engrave this for you" and a customer who can already see theirs.
Text
Add a text decal, connect it to a text control, and whatever the customer types appears on the model.
You set where it sits, how it is angled, how large it is, and which font it uses. Fonts are registered in the same place as the panel's fonts, so you can offer the typeface you actually engrave in rather than an approximation.
Position it by dragging in the 3D view rather than by typing coordinates.
Images
An image decal works the same way, with the picture coming either from you or from the customer.
For customer artwork, pair it with a file upload control. They upload a logo, it appears on the product, and the uploaded file travels with the order so you have the original to print from.
For a fixed set of designs, connect the decal to a dropdown of images instead, which gives them a choice without the risks of arbitrary uploads.
Placement
Decals project onto the surface, so they follow curves rather than floating flat. On a curved mug or a moulded case, that is what makes it look real.
There is a projection angle, which controls the direction the decal is applied from. Getting it right matters on anything that is not flat, and it is worth a minute of dragging to check the result from several angles.
Like everything else, decals can be conditional, so the engraved version shows the engraving and the plain version does not.
Practical advice
Set limits on the text. A name field with no length limit will receive a paragraph, and it will not fit. Set a maximum length on the control, and check the longest allowed string still looks right.
Decide what you will accept before you offer uploads. A customer uploading a photograph for laser engraving will be disappointed by the result. Say what works, in a message element next to the control, before they upload rather than after they order.
Charge for it. Personalisation is work, and it makes the item non-returnable. Attach a price to the option that enables it.
Check it in Play. Type the longest name, the shortest name and an awkward one with unusual characters, and look at all three on the model.
What your workshop sees
The customer's text and their uploaded file both travel with the order. The Order review page shows exactly what was configured, and the order PDF can carry it in a form suitable for whoever makes the thing.