"It's kind of an addictive thing," Jenny said.
Lisa has four children under 11, and Jenny has three under nine. Both become accustomed to text messages coming in at two or three in the morning as the other works on their design.
"Lisa's favourite saying is "sleep is for the weak"," Jenny said.
She said the workload could be so gruelling some competitors start two years ahead and just wait for a theme that suits them.
Previously they have both entered the children category, but this year Jenny applied her talents to a menswear garment.
"The idea I had fitted well into the theme, which was uniform."
She said her husband quickly turned into the fit model.
"I've forced it on him before so he isn't too averse, but for the show they have models and dancers, so he's off the hook," she said.
186 outfits are picked to compete each year, with half coming from overseas competitors.
Jenny's construction incorporates more than 5000 computer keyboard keys and she said she ended up having to take more than 70 keyboards from a local recycle yard.
"I took a few away and then I kept appearing and taking more. Most of them were covered in dirt. It's amazing what's lurking under the keyboard. I had to pry the keys from every keyboard."
Thankfully Jenny has three sons who were eager to help out.
"I've lost a multitude of screw drivers; don't look for a flat-head in this house," she said.
Jenny said the greatest relief was to learn that all keys are the same size, measuring exactly 18 millimetres squared.
Lisa didn't get off easy for her outfit either.
Her construction incorporated more than 300 coloured pencils, and was entered into the imaginary friend-themed children's category.
"I have a VIP card for the dollar shop now. I cleaned them out a few too many times," Lisa said.
She said the inspiration came from her children's overflowing stationery draw at home.
Lisa had previous experience designing outfits, having won the first Ag Art Wear show at Fieldays.
She said the biggest challenge was making the outfit durable enough to be mailed down to Nelson and worn 20 times without falling apart.
"One of the competitor's outfits in our first year broke in the mail and couldn't even be entered," she said.
Lisa said all of this has contributed to her toolbox being more impressive than her husband's.
This wasn't the only compromise the sisters' significant others have sustained; Jenny's workshop has already claimed half of her husband's office.
"He knows one day he will be gone from the office entirely," she said.
Each design is allowed to be worked on by up to three designers, but the sisters say they have never been tempted to combine forces.
"We have our own angles," Jenny said.