What kind of personal lubricant should I use to help with the design? Preseed or a simple water-based lubricant?

Some vaginal lubricants (containing petroleum jelly or petroleum jelly) have been reported to be toxic to sperm. These should be avoided.

A water-based lubricant would be adequate. Some fertility clinics recommend simply using a small amount of mineral oil (often found in lubricants)

As for Preseed, it would indeed be a good choice. Indeed, some studies have evaluated it as the lubricant with the least impact on spermatozoa (vitality and mobility) in the laboratory. It could therefore be a priority if you want to maximize your chances

The major difference with other lubricants is that it does not contain glycerin. However, the science is not yet conclusive that glycerin is really harmful and lubricants containing it can still be used.

Mineral oil does not harm sperm according to several studies, which is why it is also a good option