Best just to go to your local printer and have one custom made. I have been printing for over 20 years, most of the ones I have done are 5 1/2 x 8 1/2. Usually 2 part, sometimes 3 part. An 8 1/2 x 11 is a large sheet for replacing a battery, replacing blades, etc.. Some also put on a storage fee on the order if you do not get your equipment in so many days.
Do it the other way.
And have a line that says storeage 14 days free
Then under it Excess safe storage fee.
That way the custome thinks they are getting X days for free and you are a good bloke
written the other way you are gouging bastard trying to screw them for every cent.
OTOH
Never found a preprinted form that works and they seem cold and mechanised to the customer.
Itemising the labour always looks silly and can generate lots of arguements because "I can take the blades off in 3 minutes why have you charged 10 ?"
Item lines like "workshop sunderies" also make most peoples blood boil where as 528-000321-A / clip $ 5.95 will always be accepted even if the clip, is a speed washer and cost 10¢
I oft slip a - A after a pert number because it makes the part you fit look like an upgraded part
If you fit after market parts you should also have a printed line
" Unless otherwise instructed ,to provide the best service at the lowest possible price we use certified after market parts where parts of guaranteed OEM quality or better with suppliers warranty are available"
Or similar.
That way if you itemise out parts with original part numbers and the customer checks them they will come up with the original price & see you have saved them money and if they find cheaper parts then they are the parts of dubious quality which do not come with warranty.