Published: 14:35, 21 August 2019
| Updated: 17:06, 21 August 2019
Church organiser Annmarie Huigen, who was instrumental in setting up the hub for volunteers, has announced that the book will be opened on Friday.
It will also be a donation point for anybody wanted to give funds to Lucas' family.
Hundreds of people have commented on social media paying tribute to the "blue eyed boy".
People have also started to lay flowers near Richborough Road which was cordoned off by police this morning. One card simply reads 'Lucas with love'.
But even more have started to build up beneath a weeping willow tree on Sandwich Quay, close to where a vigil was held on Monday night.
This is believed to be the desired area for floral tributes to be left.
A red rose plant was among the first to be placed by a group of volunteers Stevie Henry, Alison Trevellion, Samantha Tipton-Lee, Daniel George and Anne Lillywhite. It was donated by Archers Low Nursery.
The strangers who have now become friends have been helping in the search since Saturday night.
Ms Henry and Ms Trevellion have been delivering food to the family every morning. Ms Tipton-Lee and Mr George have been camping out over night. They say they've walked over 150 miles during the five day search bid.
Mr George said: "We hope that this is closure and that we can finally get this little boy back to his family, and we can get the rest that everyone needs."
Ms Henry said: "The community in Sandwich has really pulled together but so have others from out of the area. They've come from all over."
Kent Fire and Rescue Service's Mani Cook speaks after the discovery this morning
They say they have spoken to the family who have agreed that this should be a space for people to leave tributes if they wish. It is the Weeping Willow tree next to Sandwich Medieval Centre.
Rescuers made the discovery at 9.15am this morning and the police have thanked everyone for their support.
Chief Insp Mark Weller said: "It's with a very heavy heart that we found a body this morning in the river within the search area.
"At the moment we are working on the hypothesis that it is Lucas, but we are awaiting on confirmation.
"The family have been informed - that's the very first thing we did - they have been kept informed throughout.
"We are working with them now and a family liaison officer to help them through this incredibly traumatic and difficult time.
"We have had great support from the community in terms of searching and support to officers. The Salvation Army and Red Cross have been absolutely amazing.
"The search and rescue teams and divers have done an absolutely amazing job and I am incredibly grateful.
"Thank you to the public who tipped out on mass and really helped to maximise our chances of finding Lucas at that early stage but unfortunately, it wasn't to be.
"We are looking after our officers as things like this are traumatic, but of course no where near what the family are experiencing right now."
"No matter the expectation, when it's actually confirmed that this is the outcome it comes as a massive, massive shock."
Mani Cook, Kent Fire and Rescue Service area manager, confirmed Lucas was found with in 100m for the incident, said: "It was a fairly long search but we would have continued had we not made that discovery this morning.
"The community has been phenomenal - it has been touching that they have taken such an interest in locating this little boy.
"Our thoughts and prayers go out to the family, friends and this community. There is a lot of emotion out there this morning but that's to be expected after such a long, intense search."
It wasn't just professionals helping in the efforts. Volunteer organisations including the RNLI and Kent Search and Rescue(KSAR) have also helped with search efforts.
Stewart Baird from (KSAR) said: "We would like to offer our sincere condolences to Lucas' family at this sad and difficult time.
"This was one of the largest search operations seen in Kent and involved over 100 of the emergency services including the volunteer specialists of Search & Rescue, HM Coastguard and the RNLI.
"The joint emergency service operation worked extremely well and co-ordinated by Kent Police with the support of Kent Fire & Rescue and Kent Search & Rescue, a huge area was searched systematically over the five days Lucas was missing.
"KSAR deployed teams each day from dawn until dusk and worked tirelessly with Police, Fire and Coastguard colleagues to bring Lucas home. KSAR crews are entirely volunteer and all took personal time from work to ensure the search operation was at full strength every day.
"We would also like to formally thank the residents of Sandwich, Deal and surrounding areas as well as the wider public as a whole.
"Their support, donations and practical offers of help was truly amazing and in the darkest times helped all the rescue teams keep the operation running. This has been a very distressing time for everyone involved and our thoughts are with everyone touched by Lucas and his family."
Speaking this afternoon Ch Insp Mark Weller of Kent Police said: "Following the discovery of a body in the River Stour at approximately 9.15am on Wednesday 21 August, formal identification has taken place and I can confirm the body is that of missing Lucas.
"It brings an end to our search and I would like to echo Lucas’ family’s message of thanks to those who came out to help search for him in the last few days. The community support we have witnessed has been heart-warming, even in the most tragic of circumstances.
"I’d also like to recognise the efforts of our partners from Kent Search and Rescue, Kent Fire and Rescue Service, HM Coastguard, the Royal National Lifeboat Institution and all the volunteers who assisted in the search for Lucas.
"While the search may have ended, our support to Lucas’ family continues."
The death is not being treated as suspicious and a report is being prepared for the coroner.
Sandwich's town flag is currently flying at half mast
A spokesman for the town council said: “The Mayor, councillors and staff of Sandwich Town Council would like to offer our deepest and sincere condolences to the family of Lucas Dobson at this heart-breaking time.
"The council would also like to thank and acknowledge the incredible amount of work and effort applied by the emergency services, rescue teams, local businesses and members of the local community who worked so hard to find Lucas; the strength of our local community has truly shone through at what has been an incredibly difficult time.”
A JustGiving page has been set up to help the family.