My first! Just want to encourage those of you who are intimidated to try like I was to give it a go. I laced a UDC hub to a 24" Alex DX32 rim for my Rowing Muni in a 4X pattern using THIS tutorial. It only took about and hour and came out very close to perfect. Riding will tell how well it holds true. If you’ve wanted to but are intimidated, GO FOR IT.
that takes some skill and bravery well done
I brought my wheel to my local bike shop this morning to have them do it. 
I was going to do it myself, but between buying $18 of spokes, a spoke wrench, and anything else I might need, I figured I’d just spend the extra and have it nicely done and trued. They said $50 for me since it’s for the Charity Ride, including the spokes, taking the rim off the 26", and the rim off the 20", and puting the 26" rim on the 20" axle.
If it was just building one wheel, I might have done it myself, but I just don’t have the patience and time to do it all.
Next time, I will do it myself.