I took a couple of minutes to make a soldering stand, which appeared to work really well. This helping hand is solid and portable: simply assemble it on the spot and on the fly in less than no time. An important limitation of the design is that it doesn't allow 3D-rotation. See step 1 below for the design features.
After completing the work I checked for other Instructables on easy soldering stands and found quite a number of alternative approaches to the same problem. However, I didn't see a similar design with a clamp, therefore I decided to document my approach in this Instructable. For completeness I provide a list of alternative solutions in Step 2 of this Instructable.
What I also found is that the clamp type I've been using has been applied by a number of other Instructables' members, for multiple products ranging from a camera and phone support to a towel holder. An overview of those Instructables is provided in Step 3 of this Instructable.
If you appreciate quick fixes like this 'Instant Helping Hand' you might also enjoy the 'Light Heavy Duty Handle' (CC BY openproducts, 8 July 2013), which can be made in a minute as well.
Step 1 below highlights some of the design features of this easy soldering stand, Step 2 elaborates on helping hand designs by others, Step 3 highlights the same clamp type in different applications and Step 4 explains the CC BY NC SA license of this Instructable.
Step 1: Design Features
The plastic presses (orange) are smooth enough not to damage the PCB.
On the plank two clamps were fixed, but the second one I didn't use at all. For small PCBs one clamp is enough, for larger PCBs two clamps might perhaps be helpful.
Further development: if your piece of work requires rotations then I suggest to fix multiple clamps on a board at different angles.
Next step shows alternative approaches to a soldering stand or helping hands.
Step 2: Other Designs by Other Instructables Members
Third Hand for soldering by blhack (CC BY NC SA, 29 January 2014): Alligator clips on adjustable coolant hose segments;
Soldering Station by dr_weidinger (CC BY NC SA, 6 July 2013): Alligator clips on heavy gauge wire;
Helping Hands for soldering by shaggs31 (Public domain, 19 December 2011): Alligator clips on gorillapod camera tripod;
Homemade Soldering Stand by aessam1 (CC BY NC SA, 11 August 2011): Alligator clips on wire from metal clothes hanger;
Helping Hands by musick_08 (CC BY NC SA, 22 January 2010): Alligator clips on coax cable;
Third Hand++ by rstraugh (CC BY NC SA, 21 October 2007): Alligator clips on adjustable coolant hose segments;
A different design of helping hands by frank113 (CC BY NC SA, 17 June 2006): Clothespins on wire easily bendable yet firm;
The next step lists other members' Instructables where clamps are being used for various purposes.
Step 3: Other Uses of the Same Clamp
Magnetic Phone Camera Base by grinderman (CC BY NC SA, 12 February 2014);
Tripod Clamp by jakpot90 (CC BY NC SA, 22 July 2012);
Clamp-mount for multiple angles with one camera by ossum (CC BY NC SA, 23 June 2012);
Clamp On Paper Towel Holder by RadBear (CC BY NC SA, 1 June 2007).
Suggestions for storing the clamps:
Clamp Rack by RadBear (CC BY NC SA, 23 May 2008);
Instant storage for Spring Clamps by TheExterminatingDalek (CC BY NC SA, 14 February 2014).
The next step elaborates on the CC BY NC SA license under which this Instructable has been released.
Step 4: License
This Instructable partly builds upon work from a number of other Instructables members: other approaches to soldering stands (by blhack, dr_weidinger, shaggs31, aessam1, musick_08, rstraugh and frank113) and alternative uses of the same clamp (by grinderman, jakpot90, ossum, RadBear and TheExterminatingDalek).
Republishing this Instructable is allowed for non-commercial purposes provided that the same license is used (CC BY NC SA) and it is properly attributed (cite the name openproducts, link to www.openproducts.org, www.instructables.com/member/openproducts, or the original Instructable). For other arrangements send a Private Message through the instructables member page (www.instructables.com/member/openproducts).
If this design infringes any rights then refer to Article 28 in the Terms of Service (www.instructables.com/tos.html).